I was actually thinking about buying Remarkable Paper Pro after Christmas. Not necessarily for the colors but just to have a portable e-ink tablet to scribble on and organize myself a bit better. In the end, I went with Supernote Nomad (A6X2). The build quality is not as good, the display does not have colors, and there is no backlight. But, for my use cases, it fits perfectly. I have found myself taking notes left and right, mostly during meetings.
What swayed me in the end was the software and repairability. Supernote actually released their syncing backend as a Docker image, so I can just roll my own and never have to touch any third-party cloud. All of my notes just live as normal files on my home server. The repairability is similarly open - Supernote sells all the replacement parts on their website. I guess this is the reason the build is not as nice as any Remarkable. But, for me, this sacrifice is worth it, given I plan to use the tablet as long as it can take me.
Bit late reMarkable is running Linux and the community is providing tools like https://github.com/ddvk/rmfakecloud
That's a pretty cool project. But with it living in the grey area of not being really supported by Remarkable, I would be skeptical if Remarkable does not block it down the line.
Supernote has full-fledged Linux support in the official pipeline. It has gotten postponed quite recently, so the devices still run on their customized Android distribution only. But even in the current state, I feel more ownership over my HW and SW than I would with Remarkable.
It's been about 6 years so I doubt it.
If they do though then I won't update and won't buy the next model. I can imagine them doing it for a new model for already sold one that'd be a first.
FWIW if you really want ownership and don't care much for weight the PineNote is probably the best our there, able to run Android (with root) but also Linux proper.