Signature conflicts with pre-installed GApps

I still cannot get UnifiedNlp working on my LG P880 (stock Android 4.1.2 with GApps pre-installed of course). I've downloaded the `UnifiedNlp.apk` from here, and installed it on the device with `adb install` (see also: #34 ). Can open the app, configured two backends so far (the local GSM and openBmap backend). Still, the Xposed module claims it gets a location, but that it doesn't look like a UnifiedNlp one. Checking logcat revealed:

```
W/LocationManagerService(13440): org.microg.nlp implements com.android.location.service.GeocodeProvider but its signatures don't match those in com.google.android.location, ignoring
```

So what's wrong here, and how to fix? Note that uninstalling GApps or using a different ROM is no option for me currently.

**Edit:** I've tried working around that making UnifiedNlp a system app, but the very same error remains. So whatever it is, it seems to have protectioLevel "signature" (not "signatureOrSystem"), so this work-around doesn't work around.
##

Start by reproducing the installation on the stated stock Android 4.1.2 device with pre-installed GApps, using adb and logcat. Investigate the reported LocationManagerService signature mismatch for org.microg.nlp and compare it with the com.google.android.location provider. Done means UnifiedNlp is accepted and provides locations without requiring GApps removal or a different ROM.

Written by the indexing model from the issue text.