The v360 filter has many projection formats, here the "orthographic" format.
Even less use for a panoramic photographer, but at least it supports alpha.
Wikipedia: Orthographic_projection.
ArcMap: ArcMap Orthographic_projection.
ffmpeg -i dacapo.jpg -hide_banner -vf "v360=input=e:output=og:h_fov=360:v_fov=360:w=1280:h=1280:alpha_mask=1" og_001.png
og_001.png
ffmpeg -i -180-90t0.mov -hide_banner -vf "v360=input=e:output=og:h_fov=180:v_fov=180:alpha_mask=1:w=1024:h=1024" -c:v prores_ks -profile:v 4444 -alpha_bits 8 -bits_per_mb 8000 -pix_fmt yuva444p10le og03.mov
ffmpeg -i black1024.mov -i og03.mov -hide_banner -filter_complex "overlay=x=W=1024:y=H=1024:x=w=1024:y=h=1024:x=0:y=0" -pix_fmt yuv420p -color_primaries bt709 -colorspace bt709 -color_range tv -color_trc 709 -movflags +faststart -preset slow -crf 24 -y og_1024overlay.mp4
og_1024overlay.mp4 30s.
roll X 0 to 180 yaw Y -180 to 0 pitch Z -90 to 90