Not sure if this is any help or not, but the ffmpeg v360 plugin C code after you do a build is at:
{yourcinelerra code directory}/thirdparty/ffmpeg-5.1/libavfilter/vf_v360.c
and if you look at native plugins, like color3way, you can see how they call interpolate (cinelerra/pluginfclient.C)
If you develop a way to have v360 do interpolation, we would be very happy to add a patch to ffmpeg so it can be used by everyone.
Also, looking forward to a Video demonstrating v360 usage inside of CinGG ! Phyllis