OK, GPS can be made to work. I followed the instructions in this post in the OnePlus forums.

Haven't tried the compass fix yet.

Also, I can't get Poor maps to install for want of qt5-plugin-geoservices-here, possibly because I don't have the proper repo enabled.

Ed: Poor maps will work, but care must be taken to install the correct version. In my case, running SFOS 2.0.4, an older version of Poor Maps must be installed from openrepos website to be conpatible with corresponding Jolla libraries. Warehouse app can't currently sort out these dependency issues, so manual intervention is needed in this cade. I have a lot of catching up to do in RPM package management...

Ed 2: fixed link to instructions, thanks to aspergerguy