Agreed. Google Play isn't as bad as the Apple App Store, but it is still a defacto monopoly. At least one can install outside apps - which is what you need to do to run Nostros. Unfortunately, most phone users understandably are not comfortable doing this sort of thing, and for good reason.
Discussion
I am in favor of anti-trust action. And I don't apologize the market libertarians for that stance.
I'm pretty sure it was you that had the thought experiment on WBD podcast about the libertarian island where the owner is merely protecting his or her property rights, which always degenerates into a state. It stuck with me.
I have quite a few more thought experiments on anarcho-capitalism that demonstrate regression problems!