Isolation for terminal environments

TL;DR I've tinkered with a solution based on systemd user-services: https://codeberg.org/s1m/termenv . It works as expected but I wish there was a stable solution for this. For long time, isolations on operating systems has been about isolations between users only. It was accepted that applications of a same user were able to access the same files, and interact with each other. They all have the…