My solution is to use the "Screen off and Lock" app[1]. It acts as a local Device Administrator to be able to force a password unlock. I added the widget to my home-screen where I can actually lock my phone if needed (leaving it somewhere for a period), and I can use the fingerprint the rest of the time.

Definitely not a perfect system. I wish that I could set timeouts and map the power button to do an admin lock. Also, having to use a 3rd party app for this is quite likely its own threat vector.

[1] https://play.google.com/store/apps/details?id=com.katecca.sc...