What is the pixel resolution of a human eye?

The current technology does not accomplish what you have asked for but rather the opposite of it i.e. prosphene. We can convert images to electrical signals to enable visual prosthesis, this means is that conversion of electrical signals into neural spikes is possible and if you have heard of neuralink this what they are precisely doing.

So we can convert images to neural spikes by electrodes and vice versa. But how exactly neural spikes will translate to resolution or pixels is not something which have been predicted as far as I know. The thing is human eye does not have "pixels" so its not something we can predict without significant developmet in the biotech. What we know present is sort of an approximate, we can't really prosphene an image accurately so reversing the process is likewise an unknown territory.

PS: I don't have a solid background in biotech and my answer is based on my knowledge on visual prosthesis. I would suggest you to ask this question on Biology stackexchange as there you might get a better answer from someone working in that specific field.

The upper limit on angular resolution for the human eye is about 0.008 degrees, based on the Rayleigh diffraction limit for light entering the pupil. The binocular, central field of view is about $60^circ$ vertically and $120^circ$ laterally, so if you divided that up into the smallest cells it would be possible to resolve with human-sized pupils, you'd get about 112 million "pixels."

Of course, human eyes don't work nearly that well, so this is just an upper limit. Most humans have a visual acuity which allows them to distinguish objects separated by about 1 arc minute, or about $0.016^circ$ - twice the diffraction limit, which would mean only about 28 million "pixels."

I'm not really sure what you mean about finding a physical way to obtain an answer. If you mean you want to measure somebody's visual acuity - that is, the smallest angular separation they can resolve - then optometrists do that every day. It's also worth noting that eyes don't have pixels, and that angular resolution depends on where in the visual field the objects are located, lighting conditions, etc.

What is the pixel resolution of a human eye?

The human eye does not have pixels; the way it handles colours is very different to a digital camera; the way it adapts itself to low light levels is also very different; and what we perceive when we "see" something depends as much (possibly more) on complex processing within the brain as on the image on the retina.

So your question is more or less impossible to answer because the human eye and the human vision system has little or no resemblance to a digital camera. It is like asking "if we could taste numbers, how many numbers could we taste ?".