Haha 🤣 Yes Primal is an app on nostr. There are many others, and as an aside, you can login to any of them with your private key and use your same identity and following in any of them. But just be super cautious about doing too much of that because if your private key gets compromised then you can’t undo that.
As for flagging/reporting, there is a spec in the protocol for how that’s handled. I’ll link it below. But essentially your app sends a report event to your connected relays, and then it’s up to those relays operators to decide how to handle it from there. I’m not sure how Primal specifically handles reports they receive.