Info Windows do not work on maps.
When you click on a marker, nothing happens. For example, in program TRAFI https://play.google.com/store/apps/details?id=com.trafi.android.tr shoul appear a window:

@mar-v-in , Can you comment on why are some of the code commented out? https://github.com/microg/android_packages_apps_GmsCore/blob/master/play-services-core/src/main/java/org/microg/gms/maps/markup/InfoWindow.java
This code is legacy code from the time we used the osmdroid library to render maps. It won't work if you try to comment it in again.
It's an old issue, however I can confirm that it's still not working, even on the newest versions of both MicroG and Trafi.