Linux

So, a lot of people have already mentioned that the arch wiki contains great info. What's missing, IMO is this: Installing Arch as described on https://wiki.archlinux.org/title/Installation_guide will leave you with an EXTREMELY basic system - you just have a bare command line, with none of the tools you'd use daily for actually using your pc.

This is where the learning comes in - choosing the software you need on your system, and learning how it all interacts with each other. IMO, you can be an experienced sysadmin, and never really have to deal with the details of what's going on during installation - it's the applications on top that actually do the work, and that you need to configure and run. Sure, you'll need to learn systemd and other components, but that all comes with use of the software you need, not necessarily the base system.

This is also why I strongly recommend having a second, working machine with a browser while installing Arch for the first time. A plain arch install does not come with the tools you're used to to connect to wifi, or even wired networks. and without a working browser, it can be hard to figure out how to connect to the internet. First things i had to do when setting it up were searching for the proper network tools and then choosing between desktop environments and window managers. For learning I recommend a WM, as a full blown desktop environment like Gnome comes with a whole host of tools already, but with a WM you need to set things up yourself so you learn more. (I went with Sway, but if you have an nvidia GPU i cannot recommend it - it works but with many little issues.)