How does ppu work? should i not use sprites that are 4x4 pixels?

I want to make an ant farm game. I originally wanted to make each ant 1 pixel but that was small even zoomed in so decided on 4 pixels and the land to be 10x10 pixels. I was following

Is this an issue the the code or how unity calculates size should i never use sprites that are less than 1unity unit in size?

thanks for any help.

Set the aspect ratio to be 1:1 and selected which part of image I wanted. The problem was that I forgot to set the resolution I wanted, i.e. 2048 x 2048; the actual image size was 2867 x 2867. And when I imported the image to Unity, max sprite size was set to 2048, but the actual image size was bigger. Here’s the problematic image: Imgur: The magic of the Internet / Foremost Pay Online Login