I use the ever living hell out of .git/info/exclude. Works great for scripts/Makefiles I only want locally and collaborators wouldn’t care about or be able to use.
For quite a while, I've have had a shell fcn that will take all the untracked files listed in a git status, and push them to .git/info/exclude. Generally applied after an add+commit of everything I do want to go generally into the repo.
Interested in examples of the types of scripts others collaborators wouldn't be able to use? Like scripts for PR workflows?