> Wanted to change a theme but first I had to install GNOME Tweak Tool for no reason
Windows does not even offer themes, why would you need a theme, they pick a great looking theme for their defaults for a reason, because Linux DE first impression and screenshots sell distros. Nothing wrong with Ubuntu's default no need to change it, crying about installing a tool that WORKS that takes you 5 seconds is no argument.
> still haven’t figured out how to have a system tray which many apps like Discord, Steam, Spotify, caffeinate need to run
Well, maybe take 10 second search? You need a Gnome extension for old style stray. Do these apps really "Need" tray icons to run? I think you just made that up. Ubuntu comes with "Ubuntu App Indicators" BY DEFAULT! That show the legacy tray icons. You claim you did an "Ubuntu" install, then you speak of KDE and DE switching. So, did you install Kubuntu? You are doing it wrong TM if you install Gnome on Kubuntu or KDE on Ubuntu. I have "Tray Icons Reloaded" running because I need that for my Gnome extension setup, works perfectly fine.
Refusing Flatpaks is you just adding an arbitrary limitation on yourself so you can complain about it. I personally run Ubuntu, and it comes with Snaps, and I never ever came across any app I needed that did not have a deb or a Snap. I would prefer Flatpak if I had to chose, but because Ubuntu has Snap integrated by default, I just use that until I really need Flatpak.