nostr:npub1getal6ykt05fsz5nqu4uld09nfj3y3qxmv8crys4aeut53unfvlqr80nfm is there a way to use an existing Nostr key as a new *master* key?
Discussion
We saw someone proposed a way to derive Master Key out of your nsec, but not sure if anyone supports it.
And it's not certain whether the extension will parse the same Nsec out of that Master.
So: no, unless you somehow figure what 12 words back up your nsec ;)
the existing 12 word key scheme in nip-06 is a key derivation based on BIP-39 and the derivation path that makes your nostr key is just one of the valid paths understood by that protocol
it is a bad idea to use a key you have already published its public key as a master key, as that means it may be relatively easier to get the nsec of these subkeys