You are thinking of https://opencellid.org and of Mozilla location services. You can contribute to them with the TowerCollector app.
UnifiedNLP is just one interface that can use many “backends” or “location services”, like the Mozilla one, an offline list, or even google itself via microG.
There are consumer unions with hired lawyers. In Spain there’s Facua and OCU (but the 2d one is governmental, I think)