I suspect how much we can decrease the ipd, I think that it need lenses look like the wearality which not stay at the center.
I try to measure the distance from center to the inner edge.
wearality : 23 mm.
pimax : 27 mm.
wearality : 54 mm
pimax : 56 mm.
Although wearality can have ipd less than pimax, but the vertical is less too. That mean the circle section of wearality lenses is smaller. So may it also decrease the vertical fov.
It still have some challenge for vr headset, how could they can decrease the IPD. Less IPD may hurt to the nose if you has low ipd, but has big nose.
p.s. wearality need wall behide the lenses while pimax need wall in front of the lenses to block image from other eye or display. wearality has more fov when you place the glasses far from your face, but it still need some fabric between nose to prevent user to see image by that nose gap.
lenses of pimax is very better because very clear while lenses of wearality is more opaque.