Great work. I didn’t encounter any of those screens, so you may either be ahead of or behind my now-stagnant progress.
Here’s what I’ve achieved thus far with the DHU running.
Keep in mind, you need the non-Go version of Play Services. I will assume this is the default shipped with microG GmsCore.
Logcat may have some helpful information as to what’s failing exactly.
As Creed mentioned, you need the Contacts and Calendar sync adapters for that to work. microG does not include them by default. There are modules that install them as priv-apps, but I could not get them to work with microG.
MindTheGapps (via Magisk module) worked on & off IIRC.