applesbana Seconded, would love this feature, even if it’s a little later as I’m sure the devs have their hands full right now :)
Some of the current turmoil is because, empirically, pre-release testing by Google's designated partner companies and by beta-test end users missed a bunch of issues (for example, clearly a bunch of annoying issues related to profile switching). It is possible that Google's face-unlock code also has issues (perhaps also related to profile switching!). The code on Google's OS may not be the same as what they provide to AOSP.
All in all, I would personally counsel people against buying an 8 to run GrapheneOS on with an expectation of face unlock ever working. Maybe it will! And it might even happen soon! But it also might never happen.
If that would be a deal-breaker for you, maybe hold off on the purchase. The price of a Pixel 8 or 8 Pro is more likely to go down over time than to go up, so by waiting you might end up saving money while skipping jitters.
Please note that I do not speak for the GrapheneOS project.