Non GPS OSD with Magnetometer / Compass for an indoor FPV crawler?

[CAndrewGreen]

I picked up one of these from Banggood when they were on special at around £30 to build up for FPV.

It would be pretty straightforward to add a standalone Minim / MicroMinim / Aeromax OSD with GPS, but, does anyone know a simple way to display magnetometer / compass heading when indoors with no GPS signal?

The only way I can think of is to use an old CC3d / Revo to drive the Minim / MicroMinim / Aeromax OSD.

Is there a more modern FC with integrated OSD and Mag / compass as it appears most don't have the mag / compass?