Be careful. Eventually, even with 'automatic updates' turned off, there's a countdown that after you bypass the 'iOS 15 is now available for your iPhone' so many times it just up and installs itself. I am not sure if the same happens with Macs. On iOS it eventually just gives you two options, install now or install later. If you somehow keep that from happening, the apps break, none will run without saying 'you must update to iOS 15 to continue using this app'
None of that happens on Android as I know how apps on Android check and phone home for updates--Mostly via Google Play Services, which a third-party app, NetGuard No-Root Firewall, can block internet access to, so apps don't force updates or complain about 'no Play Services on device'. You also keep Google from monitoring everything you do because that is also routed through Play Services. I disabled mobile data and wifi access to anything Google so any Google apps that run can run offline or run without phoning home (such as Chrome, it doesn't need Play Services to actually browse the 'net) and just disabled the actual apps (maps, search, gmail, etc) and put in open source or Samsung replacements. Since I don't believe in updates after iOS 7 turned a beautiful and fun UI into a flat cartoon (and Android did the same in version 5.0, Lollipop) I tend to have backup *.APK files stored on a Linux server acting as an NAS that date back to my all-time favorite version of Android, version 2.3, Gingerbread, the last truly open Android. Those apps run even on modern devices and look great today. Most are not even internet-based (music, gallery, file browser). I also saved some good old apps that stream music that work fine (Slacker, Pandora, Spotify) as well. You don't need the latest version of anything to have a useable device, and it does save resources to go as old as you can go.
Part of why I appreciate that even Google puts the SDK as well as an emulator for developers to tinker with, so we intelligent people can figure out how things work 'under the hood' as in Linux.
As for Macs running Linux, every attempt other than using Parallels ended in disaster. I had zero keyboard, zero wifi, zero sound, only the screen and touchpad. Something to do with the Secure Enclave having all the drivers missing in Linux. Ubuntu didn't work, neither did Mint, or OpenSuse or any others I tried. No touchbar, no keyboard, no wifi, no sound. I could plug in a USB hub with a C-to-A adapter and make it work if you like a spider mess of external devices instead of a laptop, but I want the laptop to stay a laptop. So I got a similar specced out HP laptop that costs far less and wiped Windows (after toying with 11 a bit) and put Linux on it.