Last time I looked into this gallium always was discontinued. I got endeavor os working on a Chromebook. The problem is you need to flash your own bootloader and you generally can't do that on arm Chromebooks you will generally want an Intel Chromebook to do this on and there aren't very many of those. The one I have also suffers from having very low storage, I think the onboard storage is like 16 GB.
To be completely honest I'm burnt out on Chromebooks as a viable platform. I made one work in college but I wouldn't really advise going down this path. I probably advise you to get a Pinetab with the keyboard cover or some other similar tablet for that niche, or find a small laptop of the more traditional sense to do this on.
Chromebooks are kind of all weird platform when you think about it, a disposable laptop that's designed just to be a web browser. Google obviously made it to trap people in their ecosystem and the only real markets where they've seen much usages in education, where the very limited Suite of tool students use often were web-based anyways and they're disposability means that if a student trashes them which is not to uncommon replacing them isn't that big of a deal.