It’s a fairly simple way to lock others out of apps that it’s surprising more developers don’t build in. WhatsApp has a biometric entry option for iOS and Android, so it’s surprising that Google Drive hasn’t yet built in the option for its Android equivalent app.
It might be because all modern iPhones have Face ID or Touch ID and most people use them because they’re so good, and because the tech is so well implemented din the OS. By comparison, even though Google builds Android, Android does not have a consistent biometric ID type across all the manufacturers’ handsets that run it. With a more fragmented software distribution and slow uptake of new OS versions, it’s probably a lot harder to bring this feature to Android than iOS, ironically.