Expat communities are a good one. "Expats in Bangkok". "Expats in Lagos". That kind of thing.

Bitcoin is useful because you're already dealing with a mad mix of currencies and cross-border fuss.

Anonymity is useful because grumpy expats tend to shoot their mouths off, even in countries where that's not to be advised.

You'll also catch a lot of digital nomads with that net, and they'd be more likely to get into the whole dev side of the Nostr conversation.