Note that Microsoft basically did this for Windows 10 Mobile but then killed it. I actually recompiled a few apps for it at that time, it worked fine. I imagine getting 95% is easy, the last 4% doable, and the last 1% virtually impossible (not to mention this is a moving target)
With catch up I mostly mean library dependencies. If Google changes the location API calls and popular apps that customers want do update, then the implementation will have to update, or the apps will crash/fail to work/etc.
See https://www.androidauthority.com/windows-10-mobile-android-a...