That’s the wrong comparison. In this context your opportunity is to create an entirely new supermarket in the same country.
No one can create a new App Store on iOS devices.
The equivalent would be buying an Android phone, which many people do (in fact more than have an iPhone).
I see that as equivalent to opening your Wal-mart competitor in a different country... there’s no competition.
If we are going down this line, I can also make some new arguments. Why do you think MS bundling IE was bad then, sure they had more marketshare than iOS but they were just improving the end user experience and now every platform comes with a browser by default.