I'd love a way to see what i actually installed as a first party install, no package manager I've seen does this, if you ask it "what packages are installed?" every manager just lists every library and other garbage, rather than the items I asked it to install, specifically. It's fucking stupid, and I can't believe there isn't a way to list those in every package manager.
So yes, a tagging system would be nice so maybe you could have it auto tag everything i install as "user installed" and the rest as "dependency for user install" or "system base image package", for example.