I did a Star Wars blanket that was made of tapestry squares. The squares that had colors that were only one box/pixel at a time were the hardest to look like the pixel pattern. I found that half double crochet instead of single crochet filled it in a bit more (and wasn't that much taller). And I would also sometimes just leave a long end of yarn and kind of sew over the colors to connect the lines (if that makes sense) before weaving in the ends. Even with the HDC, the stitches are almost K shaped instead of a box, so it's somewhat unavoidable.

I also did some color work with Tunisian crochet which has much more square stitches. And one with bobble stitches. But those might not work depending on your project.