Termux is awesome and a godsend to trivially shell out on android. But what I'd really want is boot to linux, choice of kernel and distribution, eventually pulling out an android layer on top of that if its UX is needed.
Basically an ARM(v8 64b) desktop-like experience in a phone sized chassis.
What makes this a non-starter is that normal linux applications are not written to be pre-emptable. Hence a default port of a linux system to a phone will kill the battery.
Hence the need for a from scratch effort where the SDK incorporates preemptability as a policy, and applications work off of that. Sadly, this means you cannot use the existing vast application ecosystem.
Librem is an effort in the above direction. It also seems like Fuschia is going this way.
Closest I can explain is mobile applications have to be written to understand "pause" and "resume", and the application is running from "resume" to "pause".
Your typical linux application does not. It expects to be "started" and "stopped", and running the whole time in-between.
Basically an ARM(v8 64b) desktop-like experience in a phone sized chassis.