Although I love modular solutions, I think biometrics are one of the few things that really need to be bundled with your device and locked down. At least if you care about security. If not, then don't use a password in the first place.
To somewhat answer your question, though, you should consider solutions that allow you to unlock one trusted device with another trusted device. The most common example would be unlocking your desktop with your phone over bluetooth, especially if that phone comes with its own biometric sensor. Just make sure that secondary device is encrypted.