>Everything has a different way to be closed or go back to the previous screen. Sometimes you swipe up, sometimes to the left, sometimes there is a back arrow in the top left, sometimes there is a X in the top right. When to do what is often not clear, and there is no universal "go back" action that seems to work either.

Very true. I moved from Android to iPhone few months ago and even through the current iPhone I use (iPhone 11) is smaller than my Android device (Samsung S20 Plus), I can't use it with one hand.