if someone went to a phone store with a stock graphene on display and anything else next to it, which one do you think they'll choose?

People consider the phone features too. For example Huawei has built a really solid following due to their phones' quality and that following didn't go away when Google started sabotaging their phones. Eventually banking apps started releasing versions for Huawei AppGallery (the Huawei Android app store).

So the Google monopoly can be bent if there's sufficient demand.