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’m pretty sure it’s akmod-nvidia-470xx, would have to try it to see if it works.
750ti actually fell under Maxwell, and RPMFusion just split it off into akmod-nvidia-580xx for GTX 750/800/900/10 cards.
I think I faintly remember running a 600 card on linux back in the day, so no reason it shouldn’t work.