This isn't a guide, just something i think may help. To install Steam on an Arch-based distro in most of the cases a simple sudo pacman -S steam will do just fine.
The installation will ask you to select a valid vulkan package from a list. And in most of the cases that's just fine... most of them.
Then you have your very "picky" old nvidia GPU which works only with a specific old nvidia driver and if you try to install anything else, there will be a conflict. Now you can try to remove the old (working) drivers and try your luck. But looking online i find a simple way to skip this passage and install Steam.
sudo pacman -S steam --assume-installed lib32-vulkan-driver
I get if you're buying 5080 and up hardware, there's no other competitors there. 5070 and lower, buy AMD or Intel. 9070 (xt) are great graphics cards. The 9060xt is great. You can go down to 7600xt, A770, B580, etc and have a graphics card very capable of gaming and they work straight out the box. No proprietary driver frictions. I use a 9070. I'll be good for another 5+ years. GPU upgrade. Maybe a CPU upgrade since I'm AM5 based. No motherboard/memory changes
I love my 9600xt. 16gb of ram is more than it will ever need. Also getting the same performance as my 6800xt at about 30-40% of the power, the fans barely turn on.