Poor Man's devenv

devenv is great. Declarative dev shells, hooks, scripts, tasks. At work, using nix is fairly uncommon, so I don't want to litter everyone's repo with devenv or shell.nix files. Devenv can also be slow to init, and enter, especially on a fresh machine or after a devenv.lock update. Sometimes I just want a shell with the right tools, fast. I used to run nix-shell -p <my tool> but after doing it 10…