they can be, and most of the libraries implement them, just that none of the clients implement the interface for it

in actual fact, the code to do it is part of bitcoin libraries - they are all 32 byte long random byte strings and can be derived imprecisely from 12 or precisely from 24 words (12 word keys only have 128 bits of entropy)

nostr:npub1ye5ptcxfyyxl5vjvdjar2ua3f0hynkjzpx552mu5snj3qmx5pzjscpknpr wanna be the first major client dev to include nip-06?