I have used Kindle eReaders for 12 years or so. My first was the Kindle 4 non-touch, soon after replaced by a 7th Generation or Paperwhite 3. Not really replaced though because the K4 became my office Kindle where it's lack of a front light wasn't an issue for me while the PW3 was my home Kindle which I mostly read at night.
I've been a loyal Kindle user over the years since. I've purchased hundreds of books on them and read a decent number of those. I was always conscious that I didn't really own those books due to the DRM locks imposed on the data and at any time Amazon could decide I was not allowed to read them anymore, without refund or recourse. It was a brewing concern but never really boiling over into action until the news that Amazon were removing the facility to download books via their web site, no doubt seeking to make it more difficult to remove the digital locks on the files.
I took the opportunity to back up my Kindle data before the deadline using a script that automated the process so now the possibility that my access to this data could be removed at any time is no longer a concern. This does mean that I cannot consider purchasing more books as keeping my data safely on my own systems is no longer possible (although I believe there may still be a way to do it with extra steps but haven't yet tried it).
Notably I don't class my Kindles as "my own systems" because Amazon have ultimate authority over what I put on there and what I do with it. This is also no longer an acceptable situation so I have remedied that through jailbreaking my Paperwhite 3.
I followed the guide on kindlemodding.com which is clear and well documented, although still quite far from a single-click solution. It was mostly smooth although I struggled with one step that actually installed the "winterbreak" jailbreak and searching online found others just suggesting to retry it until it works, sure enough this did work eventually after a number of attempts.
Once the jailbreak was installed I loaded up KUAL which appears as a book in your library but acts as a launcher for other software, and also KOReader which is an alternative eBook reader with more advanced functionality than Kindle's own software. One interesting benefit of using KOReader is that I now have dark mode on this kindle, which is available on newer models but it was never supported on my old Paperwhite.
I can now manage my library using Calibre Ebook manager and look to source my books from a few online stores (always legally of course). It is more work than inside the Amazon walled garden but I think the extra control is worth it.
I also later found a Gemini plugin for KOReader which I have installed and found to be much better quality than I expected. This allows me not just to read Gemtext sites, but browse them, online, in real time. I've always enjoyed surfing the Gemini for long-form content but on an e-paper display *chef's kiss*.
So what about my Kindle 4? Well, this is on a todo list. It is still working, albeit waiting on me to fit a new battery since the original one is unacceptably bad at holding a charge these days. Unfortunately I understand the process to be quite fiddly, even compared to the Paperwhite 3 that I have already upgraded #righttorepair. Jailbreaking this device is a no-brainer though, it is a few years out of support by Amazon so even using it within their ecosystem is quite difficult now. I do want to keep it going though because it has *physical buttons* for turning pages that are the envy of most later released eBook readers. It also benefits from a very simple uncluttered UI that really could not be improved on, Amazon have proven this many times since!
I do intend to keep these devices going as long as I can, although they are both a bit long in the tooth and I would benefit from many later advancements in eBook technology and design by getting a new ebook reader, one nice thing about them is they do seem to last a very long time and that is ultimately quite good for the planet, perhaps not as good as like an actual paper book but still, compared to the mountains of short-lived tablets in landfill already they are a less pressing concern.