Really the only requirement for Eurovision is to be part of the European Broadcasting Union, which extends out of Europe. Hence the inclusion of countries like Israel, Azerbaijan, and even Australia.
I like the way kde does it. On first install it gives a slider with how much analytics you want to send. I just do all of it because I trust KDE, but it's nice that it asks you. They probably have some pretty good data.
You seem to have a misunderstanding of how Bazzite works. It's just a custom Fedora Atomic spin that includes things like the deck firmware updates, drivers, and gamescope. It does not run SteamOS in a container.
"Free" memory is actually usually used for cache. So instead of waiting to get data from the disk, the system can just read it directly from RAM after the first access. The more RAM you have, the more free space you'll have to use for cache. My machine often has over 20GB of RAM used as cache. You can see this with free -m. IIRC both Gnome and KDE's system managers also show that now.
Ginger chew