All the way back in Android 5.0 Lollipop, Google added a 'Trusted Face' mode to Smart Unlock, giving all devices a slightly-secure way of unlocking with the front camera (the easily-fooled face unlock in Android 4.0 doesn't count). However, many people on the latest Android Q beta are having issues with it. If you're in that group, don't worry, there's a fix you can try. Read More
The Lollipop Smart Lock functionality is pretty cool. You can have the phone stay unlocked when it's connected to a trusted Bluetooth device, in range of a certain NFC tag, or when it sees a trusted face (presumably yours). Trusted Face mode in particular is quite cool, but it's not necessarily as secure as a PIN or pattern lock. You can, however, temporarily switch to the secure lock screen with a single tap.