I just use an iPad Air with Goodnotes (notes app) and Kindle (e-reader), in exactly the same way you use the Remarkable.

These Remarkable tablets seem awfully expensive for what they provide, almost like "lifestyle gimmicks" like those minimal Light phones which cost as much as a smartphone.

How people deal with distractions is largely on them, rather than the devices. People shouldn't need to buy a stripped down (but premium-ly priced) device. You can probably just take another product and configure it downwards (disable notifications, remove apps, set app timers) if focus is such an issue.

"Feature packed" - remove apps you don't want, configure UI of what you do want.

"prematurely obsolete" - Remarkable are already on a 2nd device. Who's to say there won't be a third, fourth, fifth?

"demands way too much attention from users" - just turn notifications off.