As suggested by FinalGlideAus, I tried a GoPro lens on my HS1177 FPV camera. The result is something in between a 2.1mm and a 2.8mm, and I like it a lot. See for yourself!
I am told that this does NOT work on the RunCam Swift because it is slightly different dimensions than the 1177. I am told that the lens will screw in, but it hits the sensor before the image comes into focus. I haven't personally verified this, though.
The exact lens that I ordered is this one, but you can find the same product all over eBay and elsewhere on the Internet.
