Are you truly locked in?

I still have a kindle 4 from 2011 that works fine. If you have a lot of Amazon only ebooks, there’s nothing stopping you from keeping an old device for those.

I switched to a Kobo and have zero regrets. It has overdrive/libby support and I can check out books from my library directly to it. The Kobo store is fine as well and I can maintain a calibre library for everything else