Option to unlock the app via PIN/Biometrics

[EmmaTellblom]

Add a setting so that the user can protect their data even more by locking down the data. If setting is activated user should have to enter their biodata/pincode (not sure if we should use phones capabilities or add our own) to access the app.

New dialog before the main dialog.

[serrq]

The best numpad I ever used comes from Unstoppable Wallet by Horizontal System (github and fdroid). Imho.

[carstenhag]

Quick check on our options:

• Don't implement this, make the user rely on the OS & other locking apps: Android 15 provides a native way of locking/hiding apps. Before Android 15, features like an app lock were available only for some OEM.
• Implement this, secure/unlock the app via the device's credentials. Apparently only supported on Android 11/API 30: https://developer.android.com/reference/androidx/biometric/BiometricPrompt.PromptInfo.Builder#setAllowedAuthenticators(int)
• Implement this, require the user to use biometrics to unlock the app, with a mandatory PIN/Pattern fallback. Afaik we shouldn't be API level-restricted here.

IMO, the last option would be annoying/too much for the user. Waiting for everyone to get Android 15 also doesn't seem to be the best option. Implementing the biometrics stuff ourselves would not be lots of efforts, but could be spent elsewhere.

So for now I would direct you to check if your phone already supports this natively, or to one of the many (well-rated) app locker apps available.