Google uses a new kind of Face Unlock on the Pixel Devices started with Series 4 that ueses additional Hardware Sensors to improve the Security on Android overall. But as long as Google keeps that Tech inhouse and doesn't makes it a new Standard are all Devices running Google Services and Android 10 unable to use Cameras to unlock the Device with Smart Lock. Huawei and other OEMs might have implented non-Standard Unlock Methods, but that will not be supported by Google or to be clear, on Smart Lock. So SONY could add a Face Unlock like Hua-way or Sam-dung, but that would be just as unsecure as it is on all non Google Devices...
In My Opinion did Google a mistake with that Step on Android 10, they should have kept the old Face Unlock with some optimizations. But who knows what comes next. Fingerpint readers also took their time to come into Android (HTC One Max was early in 2013 while Google had the Nexus 6 2014 with no FP, and the Nexus 6P even later who has brought it to Androids Open Source Code). So Don't blame SONY. Blame Google...
