How to test apps integration with Android and iOS stores

I'm developing two small proof of concept apps (one for iOS and the other for Android) whose purpose is to load an iframe containing a link to a different app. If this app is not installed on the device, the behavior should be to go the app store of the local environment and try to download it.

I have a couple of ideas on how to do this and I have even developed some code allowing me to open external apps, fallbacking etc. What I require now is to understand how to test this functionality using the real stores, since it is not obvious for me how to simulate or mock the stores in the respective emulators.

Should I necessarily create accounts on both stores?

Is the process of testing this flow on the device more complicated than 'uploading' the proof of concept to the device and testing it? (I mean: is there some kind of approval or a third party involved that delays my testing process?