The problem here is it is not a unit of length or a unit of area. It is a count. If you have a grid of 10 gummy bears by 10 gummy bears you have 100 gummy bears. Not 100 gummy bears^2. A pixel is a desecrate thing, not a continuous value like meters are and it is not used to measure area. For that you need to know the length and spacing of a pixel.
The problem here is it is not a unit of length or a unit of area. It is a count. If you have a grid of 10 gummy bears by 10 gummy bears you have 100 gummy bears. Not 100 gummy bears^2. A pixel is a desecrate thing, not a continuous value like meters are and it is not used to measure area. For that you need to know the length and spacing of a pixel.