Pretty difficult question because due to privacy reasons, it’s not that easy to determine whether the end-user is accessing through the Native app or via the Web version. When I google for a custom JS action to check whether it’s a browser or not, the answers are pretty straight forward:
You can however develop 2 different profiles in Mendix. When you can determine which profile the end-user accesses, you can log that (end-user, profile, timing) and verify the timings with your microflow (end-user, timing).
I hope this helps you.