An inspiring, simple, yet powerful workflow, and I think it lead to a beautiful and interesting result! Lovely pixelart input as well.
I just started doodling with pixels myself about a week ago in the PixaPencil app, and your work here makes me want to try something along the same lines. I've also been thinking of outpainting from a 64x64 or such already, keeping the style consistent, just to see what would appear by expanding infinite worlds from my own small pixelart seeds. Have you tried something like that?