You can probably do something with ffmpeg to crop one side, maybe even taking off the fisheye effect. It won’t look amazing because you’re locked into one fixed perspective.
If not for taking off the fisheye effect with ffmpeg, you can at least render one side and the use some video editing software to reverse the fisheye probably.
I have the ffmpeg command here:
ffmpeg -i input.mp4 -vf "stereo3d=sbsl:mr" -c:v libx264 -crf 18 -c:a copy output_right.mp4
There’s also another command you can try that just crops one side and encodes with NVENC. A little faster but the result is a little worse.
ffmpeg -hwaccel cuda -hwaccel_output_format cuda -i input.mp4 -vf "hwdownload,format=nv12,crop=iw/2:ih:0:0" -c:v hevc_nvenc -preset p4 -c:a copy output_left_hevc.mp4