You can use Nostr for your identity on SN by logging in with your nsec.
But they haven't integrated other things like relays, signing events with nsec, etc.
Discussion
Nostr login is just lipstick.
The transport layer in Nostr is just a taxi to the party.
Take the taxi, take the train, what ever turns you on… mathematical constructs doesn’t moralize.
I can’t. Do you know why?
Did you try copy-pasting the nsec?