If you're looking for a light to mount under your OFM using our Action Camera Adaptor here's a few we have come across which work well with our adaptor.
Garmin Varia UT is a great compact light.
Bontrager has various adaptors to suit their ION range of lights
Lezyne also have adaptors to suit their range of lights
If you find you don't have enough room under the OFM to get the desired angle you can add a straight extensions arm to give you more adjustment.
This is just a few examples. There are lots of others options out there which are only a Google search away.