Indeed, the link confirms Kindle supports only three ebook formats natively. Thank you for proving my point.
You mean the BN that has had a constant stream of ereaders since 2009
It wasn't constant. They do exist and did release the GlowLight 4 recently but they barely register on the e-reader market. Even back in 2015, they had only 8% of the market. I haven't seen anyone recommend them here (or on mobileread) in the last few years and anyone who has one wants to more away from them. OP himself said he has a nook and doesn't like it.
I'm just going by Amazon's naming system for distinguishing between models. They've called the 2018 refresh the 10th-gen, and it's marked that way on the Amazon page, the firmware download page, and the device ID itself.
Speaking of, the new 5.13.7 firmware looks to be a worthwhile update. Reworked UI and some smartphone gestures like swipe-down.
Additionally, try a kindle paperwhite. It's for reading only. https://www.amazon.com/dp/B07CXG6C9W
No, they do not. They only support azw3, kfx (sister format to azw3) and mobi.
https://smile.amazon.com/dp/B07CXG6C9W
Content Formats Supported
Kindle Format 8 (AZW3), Kindle (AZW), TXT, PDF, unprotected MOBI, PRC natively; HTML DOC, DOCX, JPEG, GIF, PNG, PMP through conversion; Audible audio format (AAX).
I agree about problems with conversions.
The only other brand that had this level of lock-in was Barnes & Noble but their e-reader quickly died out.
You mean the BN that has had a constant stream of ereaders since 2009, and released their most recent ones as recently as December and May? They sure haven't died out.