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Picture Password
(mybroadband.co.za)
Will android ever get something like this? From blackberry android, it was picture password. Simply amazing and never have to worry about someone peaking over and seeing my pin and safer than biometrics
Can't answer your question as I'm also trying to understand but recently Graphene OS has been in the news.
Basically there are apps that won't work if they have not been authenticated by one of Google's APIs. Which means there are apps that won't work if it did not come from the play store.