I mentioned in the past that all that is really needed is UnifiedNlp. That is the geolocation portion of microG and is available separately. It only needs location permission and that’s it. I have several ROMs with just UNlp, no microG, and everything is peachy. I don’t need or want push notifications so I don’t miss out on anything. SMS and email do their own thing and that’s all I was ever concerned about.
Now of course using microG without turning on device registration and GCM is almost equivalent.
But as you’ve all seen in many posts in these forums, people are running / want to run apps that do require some form of Google Play Services emulation. That’s just the way it is. There’s no way really that microG can be free of Google contact and yet provide the services that it does. A lot of folks, including me, use it with at least Play Store in most cases (hey, I paid good money for all those Substratum themes and icon packs that otherwise can’t be used).
So yeah, of course microG sends some data to Google. That can’t be helped, if one is going to use GCM or their account (for Play Store or Vanced YouTube f.i).
If /e/ wanted to really be Google free it would have to replace microG with UnifiedNlp. That would narrow the user base to a minority I’d wager. The constant reference to /e/ being used by mom and pop, grandma and grandpa, would be a no go as they would probably want to use apps that definitely (probably?) wouldn’t work in such an environment.
Anyway, microG also has an XDA thread though I don’t think mar-v-in and company participate much, if at all.