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
that's not what i'm saying though: what i'm saying is that AMD and intel aren't any different from nvidia, they're all the same shitheads that are happy to pretend they're pro-consumer and not evil when they have the excuse of being the underdog.
There are companies that try to not be evil (or at least minimally evil as required by capitalism) but AMD isn't one of them. Go support RISC-V and openpower instead.