They are mirroring free apps from the Play Store so that phone users can source the apps securely vs using any 3rd party mirror store. MicroG is being used to "replace" app calls to Google for location, by redirecting to other 3rd party location services.
It may not be perfect and is lacking the paid apps from the Google store, but it does indicate a growing trend towards users wanting the freedom to be break loose from the Google store. At the end of the day it comes down to the apps you really need to use daily, and many of them are not actually tied into Google services. Just always try to use unique ID and logins instead of that easy "Google sign-in" service.
See Android without Google – and yes it has apps: The Reg talks to founder about the /e/ smartphone
How the de-Googled phone works