The way I learned was by setting up Minecraft or GMOD servers for me and my friends. I would say this is a very good way to learn the basics since it is a project with a concrete end product.
I also played a LOT of Minecraft, which has commands to “cheat” with the game, like setting the time of day or giving yourself items. That also helped me massively understand the way commands and arguments work.
I don’t care about the 15 or 30% cut they take, that’s pretty standard in retail and other software stores. What I do care about though is the fact that my freedom to install whatever I like on my phone is non existent on iOS. When I will be able to install Revanced and F-Droid equivalents on iOS I may consider it, but until that happens, it’s an absolute no from me