Currently, the Proton Pass Android client and browser extension only allow unlocking via a PIN or no lock at all (and Fingerprint). However, the Linux desktop app already supports secondary password authentication. I'd like to request that an optional app password unlock feature be added to the Android app settings (can be tucked in "Advanced" for the few users who need it).

A password option would provide significantly stronger security than a short PIN, especially for users who don't fully trust their device's physical security. Many users find longer, stronger passwords easier to remember reliably than lengthy PINs. Since this functionality already exists on the desktop platform, implementing it on mobile should be feasible. At minimum, allowing the secondary master password to serve as an unlock method would achieve the same security goal without requiring new infrastructure.