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
Shred Lights make a Light Pack that is designed to attach to our adaptor
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.