Oh my…I’ll have to ask, I bet they did. Unreal.
But you’re right. Via email is easy. And I’m mostly thinking of epubs/mobi — but drm free.
The readers work perfectly fine without an account and the Poke 5 I have is a fair bit smaller than the last Kindle I had with the same size screen.
It runs Android and I also use Termux plus a bluetooth keyboard with it for a rather nice minimal writing experience.