krita + https://gumroad.com/l/krita-brushes-gdquest-lite (includes 3 pixel art brushes) + https://www.youtube.com/playlist?list=PLJSttJeQFQuNV4a4d2YMgpxfTWaJ1rsWo (set-up from scratch & example) + https://www.youtube.com/watch?v=OmnpKQITm3I will get you on the right track (maybe) <- all free