Google allows (and has) numerous third-party app stores on their devices, some of which are completely free. The app store that Google themselves operate also has lower fees and looser restrictions than Apple’s own store. Android is also an open-source platform that allows sideloading of thirdparty applications. Most device manufacturers heavily modify it to suit their needs.

There is nothing about any of that which has anything to do with whether Google is using their market power to unilaterally charge more than they would in a fair market.