Hi !
Unfortunately I have some bad news : I can’t copy android_prebuilts_prebuiltapks to my personal GitLab account, so I can’t build properly with an updated microG 
However I succeeded with manually upgrading it using @marcdw’s excellent post found here : How to install unreleased version of MicroG GmsCore - #2 by marcdw
Download source (Services Core) : https://microg.org/download.html
Note #1 : I’m now using /e/ test build from here
Note #2 : 0.2.11 had some troubles (crash in Settings), I had to fall back to 0.2.10
Note #3 : only Services Core is relevant, other are too old at microg.org or missing in /e/
If you need some details for installation please post back, I’ll be happy to help 