Solid sketch. Although it is too big, so pixelart and low number of colors wont make your artwork any better than simply painting it in photoshop. For larger images I think index painting techniques would be more suitable, they are like pixelart, but with large palette and gradients allowed.

This was drawn in Dpixed, which does not even allow TrueColor but still has 'traditional media' style tools. This marker tool that was used uses pressure sensitivity to determine which of the 16 colors I selected to use (which were in a pre-defined gradient) but it doesn't erase and draw new color if the color underneath the stylus is darker than the color being asked for by the pen's pressure. In other words, if you lightly drag the stylus over the dark brown areas, then 'behind' the dark areas color will show up, but you will not overdraw onto the dark areas at all unless you push down harder with the pen and that's assuming that the color you are drawing over isn't the darkest color of the pre-defined gradient.

Basically, you can draw as if in Krita or other digital art medium but with an indexed palette. It also auto-dithers, but I was kind of enjoying the non-dither pattern look. :)

I also made a post already about what I think of the term 'pixel art' and how the term pixel is misused and the overall community/scene is lacking a lot of historical and technical context or else it wouldn't have settled on this term for the style of digital art.