I was under the impression that ReMarkable in particular was pretty good about this. I believe they just run a custom Linux variant and you can even ssh into them.

I was really considering getting one, but I think the bigger issue for me is the LiPo battery. You can’t take the thing apart without a heat gun because it’s held together with adhesive, so in a few years when the battery doesn’t hold a charge, you have an expensive paperweight. I would pay a premium for a thicker device that used normal screws so that consumables such as the battery can be replaced easily.

(Many devices these days are similar, so it’s not only ReMarkable doing this.)