No strong opinion here, but isnt it up to the user what they put in their profile?

In Solid we had open ended profiles. That's an aspect of decentralization that I loved.

Linked data in general allows lots of fields.

Mastodon lets you add 4 fields in a quite restrictive way.

Referring to a nip for descriptions and guidance could be useful (all be it quite centralized) another way would be to make an LD type vocab that could be extended, similar to:

https://w3id.org/nostr

Ultimately first generation apps, goverrned by the NIP process will move fast and break things. 2nd generation might learn from that approach and build in a more long-term way.