Physics limits the size of the pixel also and I think the limit is a bigger pixel then current lenses.

The diffraction limit with white normal light is something like

1600lp/mm / the F stop

So at F/1 1600 would be a perfect lens. I doubt this exists in anyplace.

At F/4 it would be 400 lp/mm. Supposedly some of the best 35mm lenses are already close to this limit.

A lab could test with monochromatic light and get higher numbers but that's not exactly usefull for most of us.

Now check your films. How many come close to even the F/8 number of 200 lp/mm?