I haven't used the Modos Paper Monitor. Not even sure if it's actually for sale.

You could look at the Dasung Paperlike monitors though. Or the Onyx Boox Mira. They should be much the same (ie. they're e-ink monitors), though they are quite expensive. They've been out for years, so there are plenty of videos, reviews, second hand units, etc. out there.

I have one of the Onyx Boox Mira monitors (the 13" one). It's a bit small and cost more than I'd like, but it has helped with eye strain as someone who works on a computer all day. Speed isn't an issue. It's plenty fast for anything except watching videos or gaming. The main caveat with any e-ink monitor is that it's black and white, so you'll need to tweak things on your PC to get a good experience. That usually means putting things in light mode or high contrast mode.

Looks like a bunch of workarounds even in the concept stage

Are they even available for sale?