yes, you should be able to tag a issue, comment, proposal or commit in proposal from a repository in a note (proposal, issue, comment) send to a different repository and have a reference to it and have it show up in both places.
Similar how it works 'mentioned in' in github I suppose. 
this is dependent on this issue and:
nostr:nevent1qqsg9fdqq7djq2sc7xamt49n7zd5qu73y8pupxfqxm3s76j3r25shqqhtk8jp
https://gitworkshop.dev/repo/gitworkshop/issue/82a5a0079b202a18f1bbb5d4b3f09b4073d121c3c0992036e30f6a511aa90b80
and  

 do you think that would adequately address the need?  

 Yes! ☺️ 

Anything more complex and you'd need a cross-repo issues board, or something, which would be cool for multliple-repo projects, but I wouldn't work on that until we get the kinks worked out or you'll get drowned in change requests.

Would probably need a change in the NIP to establish linked repos in an overarching project, or something. Dunno. 

 in ngit you can now tag as many issues, npubs or other nostr references as you want using the `in-reply-to` flag.
in commit 10498b953d36304b441fcb162155c2487046206f.
There is probably a feature request needed for gitworkshop to display these references nicely.