Would you care to say any more about your experience with Vue? I've heard a lot of good things about Vue and had it on my mental "things to learn one day" list for a while. Would be really interested in hearing any counter-points from somebody who hasn't enjoyed working with it.
They had a similar issue as Python, albeit not nearly as bad, with their upgrade from version 2 to 3. It required some rewriting. They also introduced a new core concept with the "composition" API, which completely changes the way Vue apps are written. Luckily once you made a few required changes you could continue writing apps like you used to, ignoring the new composition API. I'm assuming at some point we'll be forced to change, which will suck.
One thing we do, which I don't think is as common when using Rails with a heavy frontend like Vue or React, is that Rails is not in API mode. That is Rails still handles routing, pages are still rendered in ERB, and then each page is its own little Vue app. So we can use Rails, Ruby, etc to initially hydrate the pages and inject stuff by calling to_json on it. This also means we can let Rails and Devise handle login and session, which I absolutely hate doing with a pure JS frontend.
Routing and session management are something I think Rails is extremely good with. This also means that if a section or sections of the site are pretty simple (password reset for instance) we can just render the page in ERB, no JS required.
Regardless, I still like Vue and it has a pretty decent ecosystem. If I had to go back and start again I'd probably just go with React. It clearly has the most support (and most jobs) on the front end.
I use .net mvc with a razor templating engine. But this can be used with any backend.
It makes it super easy for me to maintain all my UX in server-rendered HTML templates. I get a clean SPA with super high development efficiency with MINIMAL javascript.
The best part was I could hire any developer and they know how to work in basic HTML/JS/CSS.
Edit: Reading more, I might need to spend time looking into HTMX/Hotwire as a replacement for PJAX at some point.
What has you bother to introduce unpoly when Hotwire is included by default? Aka, what are the main things missing/better that drive you to use unpoly.
I'm not saying you should replace Hotwire with anything else - I wouldn't do it given it's the default or defacto solution.
But all of these tools (pjax, htmx, unpoly and hotwire) work perfectly well outside of Rails too. So if you're not using Rails and you're, for example, using Django which doesn't have a default solution then you can pick one of them, and I think Unpoly is a very nice one.