You can already unlock 1Password using biometrics in your Apple devices. they do ask you for your password every 2 weeks though. But I think that's a great balance.
...Unless I misunderstood what you're talking about. When I put in a passkey, 1p just asks me to press a button, not re-unlock.
With a passkey you would have one in keychain that unlocks 1p. So you will only be asked for your phone password/unlock code whenever iOS asks, but it will be used to unlock 1P. Never need to enter your 1P passphrase.
The passkey is stored in the secure enclave which is protected by your unlock code & biometrics (for fast unlock), or whatever the equivalent is for Google. You're not replacing your secret key / passphrase, it's just a different way to authenticate and decrypt vaults.
It's really more a convenience on a handheld device where entering a passphrase (mine is 20 characters) is a pain in the arse. Though, if it were available for macOS, I would use it there too.
...Unless I misunderstood what you're talking about. When I put in a passkey, 1p just asks me to press a button, not re-unlock.