I wish I could answer all your precious information, a little overwhelmed I must admit by the number of acronyms and tools mentioned; just a few broad ideas:

PWA I don't really care what Google considers as an 'ideal web app', in other words a PWA;
1- because Google has no idea of what business users need,
2- because all the buzz that GAFA companies make about tech tools (open source, specs, and so on) has one single goal: recruit the best engineers for their flagship, profitable products.

Off line access We never had any demand from any client for that
It reminds me of the "disconnected folder" in Windows XP and the "offline URLs" that some browser used to offer (eg. IE) -- never saw anyone use that and it has completely disappeared today.
If some day a client really needs that, we can easily replicate the data and .controlSource structure from VFP to the client, and add a switch to FoxInCloud.js to get the data from local storage rather than the server.
As long as you have an existing structure on the server (the VFP app with datasession, aliases, forms, containers and so on), it's pretty easy to replicate in JavaScript (scan through the structures and write JavaScript) and to keep it in sync with the server.

About the JavaScript code generated by Cuba Studio; hopefully they offer hook methods to override and/or influence the JavaScript generated.
FoxInCloud generates HTML/CSS/JS for what each is worth; in other words do in HTML all what can HTML can do, do in CSS all what CSS can do, and do the rest in JS.
The developer can override/modify almost everything that FoxInCloud generates:

• at control level, for the control itself or any sibling: the whole HTML or just some attributes, add custom CSS classes, add custom CSS rules, add custom JavaScript
  
• at page level: add custom HTML before or after the form, add custom CSS and JS files
  
• at app level: add custom CSS or JS
  

>>I love your posts for their density in acronyms and new products that take me half and hour to discover and reply appropriately.
>
>>PWA (Progressive Web Apps.) seems to be is another moving target in the Web space, off-line no longer belongs to the base requirements; any FiC app. can match the PWA baseline requirements.
>
>Yes, it does depend on who is making the pitch, but off-line capabilities were third only including a manifest and settling on home screen (which I see as technical necessity and eye/access candy) - at least in the video talks I watched. Cannot give you specific URLs, but search for Addy Osmany talking about PWA and you will find a few talks "nearby" touting the benefit of service workers and offline-first-development. (I especially liked the "Lie-Fi" description of some connections tantalizingly available, which I know from Hotspot expirience over here: Hotspot is the name Deutsche Telekom offers WLAN access via secondary, separeated guest net from own routers, access points and home routers of Telekom-landline vased routers participating in the program (if this sounds a lot like Fonero, it is, they entered a partnership with them). [See how I degress if not just trowing yo acronyms?]
>
>I first read about PWAs in Eric Elliots musings/ramblings and was not really drawn, as his focus is more on doing everything native/hybrid apps do just in Javascript in a PWA. I became more interested after realizing almost every mention of PWA included a reference to sevice workers and their necessity for offline loading in background, but as perf AND client side caching of data always was my prediliction, my reading targets might have been compromised/been less than a random sample of typical PWA articles ;-)
>
>The Lighthouse scale I encountered first on the HN-PWA comparison (PWA implementations in Hacker News, a showroom for fwks to give their interpretation/implemetation, which might be more relevant to view a framework in as the ToDoMVC list. Dunno who decides what PWA must have, but it forms at least a bullet point list to check against.
>
>Still, PWA checklist https://developers.google.com/web/progressive-web-apps/checklist shows prominently
>
>All app URLs load while offline
>To Test Load various pages in the PWA with an airplane mode enabled. Ensure the app presents some content even when offline. Use Lighthouse to verify the start URL responds with a 200 when offline.
>To Fix Use a Service Worker.
>
>How does FIC handle embolded part technically ?
>
>>
>>VAADIN (aka Cuba Platform, "An open source Java RAD framework for enterprise web applications") seems to encapsulate HTML/CSS into Java code, similar to Google Web Toolkit; works on different principles than FoxInCloud.
>>
>
>I have not worked with the Cuba platform,but read about it. My experience with Vaadin comes from Rapidclipse, aiming for Java RAD as well. While Vaadin does not boast offering a desktop app and concentrates on creating HTML web sites from Java object trees, Rapidclipse also can run a Java desktop app from the Java object tree used in Web apps.
>
>Insofar I think the comparison of FIC to Vaadin is accurate. If you look at Cuda source example

>Let’s see how we can create a dialog window of CUBA Studio with Vaadin:
>
>final Window newProjectWindow = new Window();
>newProjectWindow.setModal(true);
>newProjectWindow.setCaption("New project");
>newProjectWindow.setWidth(400, Unit.PIXELS);
>
>VerticalLayout content = new VerticalLayout();
>content.setSpacing(true);
>
>// add grid with properties of a new project
>GridLayout grid = new GridLayout(2, 2);
>grid.setColumnExpandRatio(1, 1);
>grid.setSpacing(true);
>grid.setWidth(100, Unit.PERCENTAGE);
>Label nameLabel = new Label("Name");
>nameLabel.setWidthUndefined();
>grid.addComponent(nameLabel);
>
>// add input controls
>TextField nameField = new TextField();
>nameField.setWidth(100, Unit.PERCENTAGE);
>grid.addComponent(nameField);
>Label versionLabel = new Label("Platform version");
>versionLabel.setWidthUndefined();
>grid.addComponent(versionLabel);
>
>ComboBox versionBox = new ComboBox();
>versionBox.setWidth(100, Unit.PERCENTAGE);
>versionBox.addItem("6.0.6");
>versionBox.addItem("6.0.5");
>grid.addComponent(versionBox);
>
>// add OK and Cancel buttons
>HorizontalLayout buttons = new HorizontalLayout();
>buttons.setSpacing(true);
>buttons.addComponent(new Button("OK"));
>buttons.addComponent(new Button("Cancel"));
>
>content.addComponent(grid);
>content.addComponent(buttons);
>
>newProjectWindow.setContent(content);
>newProjectWindow.center();
>// show window
>UI.getCurrent().addWindow(newProjectWindow);

>
>
>will evoke a shudder from most but deja-vu feelings from Swing or SWT devs ;-)
>Does it matter if FIC adds code to emit HTML/JS to existing GUI or Vaadin wraps HTML control "interfaces" allowing you to code against them in Java ? End result is similar, especially if you throw in a factory to create a desktop or web GUI ;-)
>
>>P.S.: not sure why you (and others seemingly) in first intent doubt of what we (FoxInCloud users and/or I) write about FoxInCloud; you don't seem to have the same doubt about 'mainstream platforms' writings as you often cite them here.
>
>I often have my doubts on "mainstream platorms" and believe am not singling out FIC. What I know is that I look more in Java/JS posts for new ideas
>
>>All we/I say or write here, in our blog or other forums is the exact truth; FoxInCloud Development Videos can help see clearly what we claim: https://www.youtube.com/channel/UCrEohAtbuf3uOXBH2pjp5Vw
>
>In examples it is easier to make things look good, so I search for things like HN-PWA, ToDoMVC, DB-Monster where different technologies are applied to identical problem. And yes, it is inherently clear that DB-Monster is particularly bad for "server-depending arcitectures" approaches compared to pure clint side SPA ;-)
>
>>Thanks for appreciating the Bootstrap responsive support in FoxInCloud anyway!
>
>If I wrote something off base and realize it, I will correct it - esp. if my misperception might turn somebody away for wrong reasons from one of the Fox offerings.