Why we don't just use mnemonics, and generate many nsecs from it? https://github.com/jaonoctus/nip06
Discussion
We have it implemented, but no one uses it.
Current users can't generate seed words from the existing nsecs. They have to restart from scratch.
It seems that NIP-06 doesn't support multiple keys in the sense that a new key is used for each new note/event. But different account numbers are a thing.