I regret buying this phone. Seriously the spec list is really attractive for the price but the os experience is so garbage. Paying 150€ more on Aliexpress for a 7T would have been a better choice I think. And dev community on this device is also so poor, we can't expect much improvement. I hope we get some custom ROM that's stable enough and where we can get everything working properly. Otherwise it's a waste of money.
I'm with you on this one I miss my Note 9 One UI. That being said the phone is still quite recent so there's time for improvements to come, RealmeUI seems quite nice.
Which version do you have? I have the CN and there is face unlock in Settings > Fingerprint, Face & Password.