So, here’s a fun update. I messed with SNES line4x adv timing to the point that my display sees it as 1280×1024. The VP30 likes it too, and is able to process it. My Broadcaster HD doesn’t like it direct fed – the image glitches every couple of seconds. But through the VP30, it has no problem taking it as 480p, 720p or 1080p.
Here’s some 1920×1080 out of the VP30:
The concept of “tricking devices” to treat the OSSC output as PC video with which they may be more compatible is detailed more in this sticky: https://videogameperfection.com/forums/topic/tips-tweaks-lx3-lx4-lx5-modes/