Like 10-15 years ago I was into linux and tried a bunch of different distros (PCLinuxOS, Mint, CentOS, OpenSuse...) and was quite happy with the, then, limited options of gaming on linux (It was the time Valve released TF2 for linux)
But time passed, I got a new PC and didn't bothered install any linux distro (because I got a small HDD and didn't wanted to split it in partitions for linux)
Back then stuff like Proton did not even exists, so today I'm kind of lost and don't know what flavour I should pick, so here I am asking for advice
A couple of relevant details about the hardware, my PC is a little bit old (i7-7700) I hope that's not an obstacle to enjoy gaming on linux I also have an Nvidia graphic card
Also, while most people just use Steam I also use GOG regularly, if that matters
Just pick a distro and give it a whirl. Don't like it? Pick another. The only way to learn is to use.