Hi! I’ve been using Fedora Kinoite (and now Bazzite Desktop) for about a year.
I’d say bazzite desktop would be a good fit for you if you want to give an immutable desktop a try. It automatically sets up an arch distrobox for steam and lutris, it even has one click installers for things like oversteer in the post-install welcome screen, it auto-updates and is generally just quite a nice improvement on based Fedora Kinoite.
Immutable distros ARE used differently, you will mostly use flatpaks for basic apps (Although a lot of people do that anyway), but any traditional packages you want to install will be done in distrobox. You CAN overlay packages to the base system, but it should be seen as a last resort.