Onyx relationship with Open Source licensing is… delicate. This could be a stopper for some.
I had a Remarkable 1 but I feel the company is trying to be the next Apple. Everything now is subscription. Shame, as The reading experience was good, writing was excellent, software was open but clunky.
With colour e-paper screens slowly picking up speed it's going to be even more interesting. Right now their quality is going to be disappointing if you expect the same quality as your phone or laptop, but it's an enormous step up from greyscale screens - and it's still getting better.
I switched to an Onyx Boox Tab X (effectively an android tablet with eink screen) and wouldn't go back.
I have the Kindle reader app and can read very comfortably all my books, with the same comfort as with a Kindle device.
But I can also take meeting notes, brainstorm, etc thanks to the writing capabilities similar to the Remarkable.
As a bonus, I can also use it as a whiteboard in video calls.
Jeepers - not sure I am going to swap my $50 kindle for that one.