I still have reservations about moving too heavily towards an SPA - we still mostly have server-side rendered pages that render with react components so we don't have to deal with things like client side routing. It's also still important for us we render most of the page server-side for performance reasons, but I'm not too informed about the specific trade-offs there in load times if we did push more rendering to the client.

I feel like there's some opportunity in the space to create a truly re-usable form library that can hook into your backend and be themed / customized to suite the look and feel of your app. There's some companies already in that space though, so I might take some time to check out some existing solutions and see if there's some kind of needs gap. What's challenging about this problem though (as I'm sure you're also aware) is that there are a ton of variability in requirements when it comes to forms - it's something I wish were more standardized but at times it feels like one of those bikeshedding topics where everyone has an opinion on how inputs show be displayed, how errors are shown, etc.