I'm working with a team that is building exactly that.
https://github.com/HORNET-Storage
I'm working on a nostr keychain/signer/verifier right now, nearly finished my v1.1.0 target:
https://github.com/mleku/signr
the idea of the tool will be that it can be adapted to be used by any project that works with nostr keys, this extensibility is part of what I'm adding with the extra minor version.