Hmmm interesting, an even harder dependency. I'll probably do it, but it would be nice if there were a standard so relays could directly support that.
Yup! Nostr.band actually has an endpoint for that: https://api.nostr.band/nostr?method=search&count=10&q=#Bitcoin
Discussion
There is actually, NIP-50 keyword search. It’s just that so far, only a few relays support it
I definitely don't recommend using that http endpoint, just use NIP-50, and w/ hashtags - why not just use '#t':["bitcoin"] filter?
Yeah I just ended up modifying the approach so that rather than only allowing users to add hashtags that are cached, they can follow any hashtag and it filters it like you described.