+1 to the idea of using teams (at least until there are good options for filtering by tag); we use it in the dotnet projects and in my experience it's worked well there. I have been happily oblivious to and not notified about most dotnet issues, but whenever somebody tagged the @dotnet/jit-contrib team I'd get a notification, and what's more Github includes metadata[1] in the cc line when it sends notification emails, letting me set up inbox rules to route notifications about issues where I'm included by team_mention (@dotnet/jit-contrib) separately from issues where I'm included individually.
-Joseph
[apologies to those of you receiving this twice; my mail client likes to drop llvm-dev from reply-all for some reason...]