Graphene isn't made to cater to what everyone wants. Face ID and fingerprint unlocking so clearly have no place in a hardened OS. "Google OS-level integration is absent" should not be suprising.
This said, you ought to be able to have BFU security with stock Android and it's embarrassing Google ships stock vulnerable.
I know! My entire point is Graphene wouldn't be a good choice for the stock OS on a mass-market phone. The Graphene devices will be great, but if Google were to replace their stock OS with Graphene there would be problems.
It's very polished and completely usable as a daily driver.
If the general public prefers unsafe phones, they can chose literally any else brand. This is never going to be a mass market phone because of the tradeoffs that are perfectly fine for the intended recipients (eg people who believe a torch/calculator app REALLY doesn't need internet access, or that their Instagram REALLY doesn't need to have access to ALL the photos/videos.
I prefer pattern unlock, which it does not support.