An interesting question indeed..depends how you go about it really! Would surely be easier artstyle-wise and on funds making all H scene characters 3D models instead of having to draw new art for each tiny movement viewed.
First person perspective with ability to look down at our bottom half and see our hands as we lift them up. Multiple reactions from H scene girl depending on what they like and where we touch. This would not need to be restricted to the H scenes ofc, but could be for all character interactions, even battle modes, to give us as deep a sense of immersion as possible.
In my mind, I can see the immense potential of VR Hentai games for the future, so I remain hopeful that the designers can implement such awesome visions!
*evil cackle at how useful the fleshlight bluetooth plugged into a hentai game could be for the H scenes*. Trust me Kinkoid, the fanbase is everywhere and would strongly support such a thing, if you could truly implement such deviance! *throws gauntlet*