thats an awesome idea! much thanks for the info!

personal insight preinstall (for ppl reading this):

• it is always better to use fdroid apps whenever possible.

i had tried mcroG once upon a time(many years ago). it didnt work for me.
possible reasons:

• project may have been less mature than it is today.
• other. (see below)

installation:
https://github.com/microg/GmsCore/wiki/Installation "Install GmsCore.apk" , "Install GsfProxy.apk"
"Please review the Prerequisites and Helpful Information before starting installation."

https://github.com/microg/GmsCore/wiki/Prerequisites
"Your System needs to support signature spoofing, see Signature Spoofing" , "[You need a ROM that supports signature spoofing.]"

conclusion:
-need to follow the specific installation instructions.

• according to the docs.. u need a custom rom(distro ie lineageOS on a supported device.)
  https://wiki.lineageos.org/devices/