I am not as well-versed in the specifics of ARM's TrustZone as I am with Intel CSME and AMD ST, but I understand many of the people uncomfortable with the latter two are uncomfortable with the former as well. I do not believe it comes with the same capabilities as CSME or ST (PSP), but I do know that earlier versions of PSP were implemented using an ARM TrustZone core. That said, I need to do a lot more reading and research on it before forming more substantial positions on it.