Personally, I wouldn't recommend immutable distros, as I think they limit our freedoms far too much, not that the way the general stack is going doesn't do that already. Not debating that here, since it's a hot and controversial topic currently, at least in the segment of the linux using population that cares about this stuff and which picked linux for that. Imo, if we do this, we'll basically make of the OS one block, from bootloader, to kernel, to initramfs, to display manager and finally desktop, especially since I'm hearing whispers of attempts at removing the tty kernel rendering being done, which will force us into using a specific compositor, desktop and so on, so we'll be exactly like windows or mac or android, so we lost everything, and then what's the point of linux?
If you want to use immutable distros anyway, I don't recommend silverblue for gaming, but I do recommend you give ublue linux a try, it has many drivers included, even some udev rules.