[hannibalhorn]

Kinda close - I use Hammerspoon to setup a hotkey that runs security(1) via popen to retrieve and paste passwords into some apps.

    /usr/bin/security find-internet-password -wgs mydomain.com

It requires the keychain to be unlocked, which can be handled with touch ID, and you can have it confirm with a "are you sure" dialog box every time.

If you really wanted to be prompted for a fingerprint basically every time, you could probably use a separate keychain that locks after 1 minute of inactivity.