Yes it is! But you need to create a new keyset to do this

You can create a keyset from an existing nsec or a new one. A keyset is a set of FROSTR "shares" (basically like keys in a multisig) and you need a threshold of these shares to sign a valid note (you choose the threshold)

These shares in the set are inherently interconnected so if you have a 2/3 and you want to make it a 3/5 you need to DESTROY the old 2/3 keyset (or at least the threshold of shares in that keysey) and then CREATE a new 3/5 keyset (with the same nsec)

Demo is here: https://x.com/bitcoinplebdev/status/1905056787771842665

I think so but @bitcoinplebdev and @cmd can give you a better answer

With these kinds of things, as always, if you have all the shares, you have the secret, and with Nostr the secret is your forever password. And the threshold of signers have to be online to work. So to use this as a password replacement you'd have to put some thought into the setup. Most people will be lazy and have all the signers on the same laptop, but that won't work for when they want to sign in on mobile and their laptop is not online. So cloud then—but it's a little tricky to setup a cloud environment that protects from collusion. So this will take time to get popular.

technically yeah though nostr integrated sites are easier. other sites would need to integrate some kind of nostr native auth, I imagine.

Woo doggie!