Correct me if I'm wrong but does FOSS not simply mean the following?
software that is available under a license that grants the right to use, modify, and distribute the software, modified or not, to everyone free of charge
source: Wikipedia
From my understanding AOSP's license grants all those rights. I think what you might be opposed to is that it isn't developed out in the open, which is a fair criticism.
its true tho ( lemmy.today ) Englisch