SPA-like user experience with back end only: Phoenix.LiveView:

This is very interesting and a project that I'll track to see how it evolves. I agree fully that for many applications a SPA and the mess of a technology stack that it usually involves is overkill.

Part of the current impl doesn't seem like it is going to scale as the DOM in a page gets larger and larger: he mentions that right now they are sending the full rendered HTML from the server to the client on every update, then doing the diff client-side. They are looking at optimizations, hopefully sending diffs from the server is one of them.

See also Drab https://tg.pl/drab The extension library to Phoenix Framework for providing an access to the browser's User Interface (DOM objects) from the server side.