I can add something to the list which is Sidecar i.e. using an iPad as secondary screen. It was a real nightmare to set it up as it’d not detect the iPad despite meeting all the requirements. I found no fixes online so I had the idea of logout & login again (iCloud) so that it might detect it.

Well, it detected I had an iPad but the connection would time out every single time. After rebooting both the Mac and the iPad (another wild guess) it kind of worked - very laggy and couldn’t use the Mac properly as clicking in e.g. System Preferences would open Finder to show me the app under Applications instead of the actual system preferences panel because of reasons.

It’s truly broken and felt like an alpha version. But this has been the trend with macOS and guess it’ll stay like this unless someone high enough at Apple decides to wake up.