It’s not tied to bitcoin other than it was created by decentralization loving bitcoiners. It doesn’t use blockchain or token bullshit as those people don’t believe blockchain is a silver bullet for any problem. You might see lightning invoices posted by users but that’s more of a client rendering the encoded data.

Fiatjaf who often posts here also stated that he would like to nostr to be used by non bitcoiners and even people who are antagonistic to bitcoin.