What I mean by “signature problem” is :
2 apps have the same signature : microG Services core (from mircoG repo) and µg UnifiedNlp (no GAPPS) (from f-droid repo). So when both f-droid and microG repo are active, i see only µg UnifiedNlp (no GAPPS).
I just figured out that clicking µg UnifiedNlp (no GAPPS) with both f-droid and microG repos on is the same as clicking microG Services core with only microG repo on (it doesn’t appear if f-droid repo is active).
So what I did was (I’m almost sure) the same as clicking µg UnifiedNlp (no GAPPS) as you did. Because both clicking µg UnifiedNlp (no GAPPS) (with both f-droid and microG repos active) and clicking microG Services core (with only microG repo active) is for installing the actual microG Services core. It’s not very clear but it’s what I understood from this topic.
Moreover, when I try to install µg UnifiedNlp (no GAPPS) (the real one from f-droid repo, without microG repo active. A thing for GPS and localization I think) it produces the same error.
EDIT to be more clear :
It’s the good thing that I’m trying to install, the “f-droid signature thing” is not very important here. What I did actually is as simple as “installing the right thing from f-droid”, but that doesn’t work “due to an unknown reason”.