On the "project introspection" side of things, is there a way to quickly show what tags are being used across a project?

There is not. Best I could think of is using ripgrep to search for

tags

in BUILD files A community member has been working on a

peek

goal to be able to see a target's metadata in an automated way, which would be relevant here https://github.com/pantsbuild/pants/pull/11347

Nice, I'll keep an eye on that! 🙏