Keychat uses a seed phrase instead of an nsec. Later, users only need to save one seed phrase to have multiple IDs. At the same time, this seed phrase also serves as the user's cashu wallet seed phrase. 
Discussion
do you plan on allowing users to sign in with their existing nsec in the future? having a portal digital identity is a key feature of nostr. many people will not want to have to mange multiple identities. i know i won't.
Or integrate amber signing. I enjoy not having my nsec all over the nostrverse
Agree here. This is the best possible outcome.
Its something I'd like Primal to integrate as well
And Amber add Nip06 seed phrase
Is there a way to login with the seedphrase I don't see it
Please wait a little longer, as the current version does not yet support importing seed phrases. This will be supported in future updates. It is still an early version.
Would have been nice, that I could use my nsec from nostr to add it to keychat to have the same npub address.