Two legit ideas

Collaborative playlists - Create, follow, contribute to playlists. Extra neat if it hooked in to whatever streaking service you use (eg. kind of like how song.link works)

Nostr leaks - Anon tips submission. App could be Tor enabled, spins up a new nostr identity when you open the app. Similar to robosats, you can re-use the key for as long as you need, but securely purge it when you're done.

nostr:note15qe9yudx6324nx3tgg5wv00e9dsqrpsks2sknwpqf8hhtunp88nq4qydjc