Given that U2F as implemented for instance by the YubiKey is stateless I am wondering if any password manager supports encrypting each individual password stored in a password collection using U2F.
This would help against the common problem that opening the password manager is already a large security risk (think CTRL+A, CTRL+C to copy all entries) and prevent giving away your complete passwords just because an attacker recorded one challenge/response communication for a single key.
U2F is not an encryption standard, but a authentication standard and uses public/private keys for authentication of server challenges.
Based on its use of public/private key signatures though it should be possible for a password manager to keep "handles" for each stored password, which after being signed by the U2F device yield the actual encryption key.
See here for a potential use of u2f for simple text encryption. I don't think it the right way to use the handle as a salt, but the general idea is there.