My wife has a 6a. A few things that she has noticed but not deal breakers. After installing a glass screen protector the finger print reader is really hit and miss. I went to enable face unlock but Google doesn’t allow it on the 6a. Custom ROM would solve that, however I don’t know about graphene. Not the best cell reception. Not a huge case selection. At least compared to non (a) versions. Battery life under heavy use is just ok.

Sunbird is more than iMessage isn’t it? I had the beta installed for a little bit and it was messenger, sms, iMessage, and a few others that haven’t used.