but nostr clients don’t make money
Who was it who said that some VC tried to invest in Nostr per se, but they left when they figured out that there's nothing to monetize about Nostr per se? It's like trying to monetize IPv4 or HTTP; you can't monetize open protocols, because they are open.
If you want to make money related to Nostr, your only option is to use Nostr to make money.