@sic_semper_tyrannis
If you can get the parcels from the municipality then you can probably give them a false OSM tag that renders and convert to show on OsmAnd via OsmAndMapCreator (then sideload them). It might be best to convert the addresses to OSM format too so they display.
Alternately there are two apps for putting QGIS projects on a mobile phone: QField and Merging/Input. They are meant for data collection but can be used to just display things as well.
If you're adding from an external source make sure you've checked the licence is OK, not everything that's "open data" is as permissive as OSM requires.
@TnSb@ISMETA that thread's bonkers, sounds like not only do they consider the tile provider non-free, but also consider hardcoding connections to OSM as nonfree.