Only one that comes to mind may be OpenVibe, they went through Wolf and I think had other backing before or after. IIRC their niche is more about data for a bunch of open social networks protocols, not nostr specifically.

Anything else I'm aware of is a Lightning company or other service that incidentally uses Nostr. There's nothing valuable about Nostr in and of itself.

One of my Nostr projects did bring in a specific angel into an overall round, but that's one persons particular interest in that particular project that I use in other (Lightning) projects.

General advice would be to forget comps, not only Nostr is too niche for comps but even if it wasn't much of what you see in funding announcements comes with serious asterisks, every deal is personal. If the platform gets any traction the funding will sort itself out.