I think (but I have not tested) that if you can use the DeDRM plugins to import your books into Calibre... You might be able to use Calibre's conversion function to make them all ePubs (which are Kobo friendly). I don't have a Kindle but I do use a Kobo and have had to run DeDRM and some conversions to make books compatible.

Good luck!

I have a Kobo Clara HD, also moved quite a few years ago from a Kindle to this. I really love the accessibility of the Kobo ecosystem. The store, while not as vast as Amazon, has good books to choose from. You can also load your own items onto it. Calibre has good support. All in all, I am happier with it than the Kindle; not worried about a book disappearing on me.

Personally I just abandoned my Kindle library when I bought a Nook. That's not particularly helpful, of course, but it's what I did as part of kicking Amazon out of my life entirely. I started buying my books from non-DRM sources.

I will say this: you may have paid for "licenses" for those books, but you don't actually own them. Amazon can rip away your access to them at any time. Were it me, I'd simply pirate DRM-free copies of the same books. Though if you can successfully strip off the DRM and convert them to open-source formats, that's just as good and carries less risk. Every time I've converted ebook formats with Calibre it's done weird stuff to the text: letters incorrectly interpreted, missing punctuation, page breaks in odd places, and enough of them to be annoying. Something to consider. Maybe that kind of thing can be corrected but I haven't yet figured out how.

🏴‍☠️

I picked up an Onyx Boox recently (specifically the Note Air 3C, which is a color e-ink tablet rather than just e-reader) and since it has the Google Play Store, I was able to just install the Kindle app. The Boox Page ($250) and Boox Poke5 ($170) make up their traditional sized e-reader lineup, and both appear to support the same thing. You could also install the Kobo Books app and make future purchases there, as well as library apps like Libby and Hoopla.

No specific suggestions, but sort of a half-anti-recommendation:

I used to own a Tolino Vision 2. It was a great device for its purpose and time - lightweight, sturdy, very pleasant e-ink screen and backlight, easy to use and didn't mind a little sand or water. Sadly I lost it.
The new models I could try out look even nicer, but they all share one common problem: half of the home screen is an online book shop that can't be changed or hidden. That was reason enough for me not to buy another one.
If you don't mind that and Tolino devices are available where you live, they may be worth a try. Otherwise I recommend you steer clear of them.

As for the DRM issue, de-DRMing with Calibre for some reason didn't work for me (quite possibly a wetware problem), so I ended up buying ePubor Ultimate, which works very well and can do a lot of things but isn't free.

I bought a Mobiscribe recently, for the same reasons. It's an eReader with an eink display, but it's an Android tablet. I installed F-Droid, and then NextCloud (to access my ebooks) and Librera Reader. I also use it for listening to podcasts (via Bluetooth, since it's an Android tablet) and taking notes with the stylus.

Anyone have experience with pocketbook? Have been looking into this myself https://pocketbook.ch/en-ch/catalog