That's why I said write down the passcode and keep it with the device. The device itself isn't important because you're not keeping anything on it. Bitwarden encrypts everything itself. To my knowledge, once you enable biometrics in bitwarden, you will not need to use the master passphrase.
Not the person you responded too, but I imagine you could likely get a custom firmware to allow biometrics whenever, if you can replace the kernel, you can generally make the device behave however you'd like.