By being given an iPhone/iPad and clicking around, you wouldn't even learn about what a filesystem is, let alone about anything else in terms of how your device works.

On a PC, just by being bored you can learn quite a bit about how the OS works; you can access devtools from a browser; you can learn tons and tons by trying to get some old/obscure game to work; you can google "how to make a game" which would probably lead you to a download page for python, which you could install and start writing some scripts; you could easily stumble upon Blender and some tutorials and start 3D modelling.

So you haven't played with Shortcuts? https://support.apple.com/en-gb/guide/shortcuts/apdb5506f698...

Or if you want Python https://apps.apple.com/gb/app/pythonista-3/id1085978097

Most of these are for education and not real work.