Hey Anders.
Interesting story.
Personally, I am using Obsidian.
I've noticed that even though Evernote has an export feature, with such a large amount of notes it could get quite tricky.
I've found this thread if you want to give it a try:
https://forum.obsidian.md/t/converting-evernote-to-obsidian/1715/5
With Obsidian, there is also an alternative to Readwise which is free and called "Kindle Highlights" I talk about that more in depth in this video:
In my opinion, trying out Obsidian (even without migrating) may be something to test because it looks more "future proof" with their markdown files...
All the best,
Matt Giaro