Combinations of bwrap, chpst, env, setpriv, and setsid can become unreadable gibberish but otherwise work fine. There's lots of similarly useful stuff that can be combined for specific needs.
This seems significantly more lightweight than bubblewrap -- it doesn't attempt to do much in the way of containerization or isolation, just remapping certain files. I feel like this could be done in a small shell script if you reduce the configurability.