Basing something around a Google OS isn’t really an alternative to big tech. Given the reaction I’d expect if a Microsoft Open Source project was the basis of an “alternative to big tech”, I don’t see why something with a Google pedigree should be treated differently.
And listing microG as an opensource alternative to Google services is disingenuous.
It still uses the same Google servers to make requests, just the client is open.
It's not possible to do push notifications for proprietary apps without making some requests to Google. The location services of microG support other providers and don't use Google. microG even replaces the Google map some apps integrate with another provider, at least it did a few years ago.
