I use it with calibre. Works perfect. Even displays the book covers (no matter where you got them) as lock screen background of the kindle. Can absolutely recommend this!

I wish to track progress across multiple platform without amazon. So far calibre web and kobo ebook readers look like the go to

Also idk about the newer ones but the old ones last forever. You might need to change their battery but that's not too hard. I got a kindle keyboard that's been going strong for over a decade now.

Also kindles work fine with calibre, you just need a different file format. Mine can read PDFs! (I do not reccomend reading PDF scans on a kindle)

Kindle doesn't work with epub which is what majority of ebooks are