I just noticed this week that Entanyia has released a new Entapano HAL 220 PL mount lens that is near-perfectly equidistant and supports a larger image circle than full-frame (so only RED MONSTRO, ARRI LF, Sony Venice could capture the whole circle). Although the camera used here is not larger format.
I just tried on a clip Entanyia provided, I stabilized in RE:Lens and did a small virtual camera motion (bottom right) to look at both side of the circle to show how straight it is right on the circle edge!!! Spectacular!
Good job mention to lens designer, notice it has a zoom spacer rings to easily adjust focal lenght and focus when moving between cameras... an old time feature-request here. Great shooting instrument.