Where I can find a pixelart tutorial in one app like this
Pixelarts is hard
I really doubt that there's any app like SL which teaches pixel art, but a more effective way would be to search online for this, since this Q&A is largely meant for programming questions only. https://lospec.com/pixel-art-tutorials
Pixelart123 is a collection of pixel art templates that are easy to draw. With over 1,000 templates to choose from, you can create any type of pixel art you can imagine. Whether you're a beginner or a seasoned pro, https://pixelart123.de/ has the perfect template for you.
Finding a comprehensive pixel art tutorial within a single app is a bit specific, but there are applications and platforms that provide extensive guides and lessons on pixel art creation. https://descargarsnaptube.org/