Except stuff in /Library/Application Support. Oh, and /Library/Extensions. Oh, and /Library/DriverExtensions. Oh, and /Library/LaunchAgents. And /Library/LaunchDaemons. Also /Library/Perl (this is Apple-provided) and /Library/TeX (this is not, this is MacTeX). And /Library/Developer.

Also, the dread of "removal instructions" that include stuff like "go through these directories and delete things that look like they belong to this software".

When available I prefer installing applications via brew as casks, since at least this way if I decide to uninstall it later brew will take care of deleting all of these associated directories. I remember using an app called AppZapper several years ago which did this but for arbitrary applications. No idea if it’s still around/maintained.

There's `brew uninstall --zap $application`[1], and there's pretty decent coverage, but it's by no means comprehensive. If you feel inclined to contribute, the process is quite streamlined, and there's a helper script[2].

I used Appcleaner[3] for many years, and it's still perfectly serviceable

I'm keeping my eye on Pearcleaner[4], which is additionally open-source and written in Swift.

[1] https://docs.brew.sh/Cask-Cookbook#stanza-zap

[2] https://github.com/nrlquaker/homebrew-createzap

[3] https://freemacsoft.net/appcleaner/

[4] https://itsalin.com/appInfo/?id=pearcleaner

Appcleaner does this. One of first installs on a fresh macos.