Lily33

Does NOT delete any files that were written to, for example, ~/.local or ~/.config from dev shell.

One of OP’s problems was,

I’m making a mess of config files and extras.

Any files created by programs running in the dev environments will remain.

NixOS containers could do what OP’s asking for, but it’ll be trickier with just nix (on other distro). It’ll handle build dependencies and such, but you’ll still need to keep your home or other directories clean some other way.

The invasion has been such a catastrophic failure that I don’t see how “escalate things again in a few years to come” is even remotely plausible, even if they do get some concession at this point.