file system, even without power usage: I install a notepad-like app on Android (think Sublime), create a file with notes on some topic, and want to send it via email to someone. Oops, where the fuck did that file go?

You are doing this like a power user. The correct way is to use the share button in your notepad app. No need to mess with files.

keyboard is something I use daily, so now three (or more?) layers instead of two can be irritating. fair point would be that I never tried a Mac, so can’t speak specifically about this case, but all those Ctrl+Alt+fuck-how-many-more-letters? shortcuts in some apps do drive me nuts (that extends to web apps too)

Again, power user. Most people don't use keyboard shortcuts at all, apart from maybe copy/paste, but even there I mostly see people right clicking and selecting copy or paste.

let’s add to this pile: fucking Android settings. Even with me being a software dev, I usually just go to Settings and use text search to find whatever setting I need at the moment, because it never is anywhere I look for it

Again, power user. The search is exactly what you are supposed to use. The directory structure is mostly there for power users who aren't searching for one single setting but want to go through each setting of a category to potentially modify every single setting possible in regards to one topic.

What you are doing is taking your pre-learned ways from one OS (probably Windows or Linux) and trying to use another OS as if it was that first one, while ignoring the much more intuitive ways to handle that new OS.

Edit: That's also kinda understandable. If you are a power user, you can't be not a power user, and of course you want to apply the skills you learned for a different OS, even if they don't exactly work for the new OS. That's natural, but it's not a failing of the new OS.