I suppose you are correct there. Maybe try a privacy screen protector or use a password. It would be harder to catch each symbol with either of those.

If you have GrapheneOS, I'm pretty sure you can randomize the numbers on the pin. You can also set a password instead of a pin and disable biometrics if you use stock Android. All the more difficult to obtain access.

For banking/crypto, I assume a wallet app would allow you to set an app password/pin.

How?