Start with

• Linux Mint Cinnamon

OR

• PopOS

For all your gaming needs, there's a Steam app you can download from whatever app store or flathub, or download/install directly.

• Heroic Games Launcher

• Lutris

• Piper for changing gaming mouse settings

I went from Windows to Mint Cinnamon, to PopOS, to PopOS Cosmic Alpha for the last year on both my laptop and desktop. PopOS and PopOS Cosmic Alpha have been great, minimal issues for me on Cosmic with gaming but there were a few hiccups or delays with newly launched games, more so an issue with Nvidia drivers than the OS. For example I had to wait a month or two after Starfield launched because there were bugs with the Nvidia drivers.

Protondb is a great resource both for checking if a game runs well on Linux, and also checking troubleshooting steps if you do run into an issue, there might be some advice on what worked for other people to get a specific game running.

Also avoid Razer or Corsair gaming mice or do your research on the specific model before buying unless you want headaches with not being able to edit the RGB settings. Best if you still have access to a windows machine if you want to own anything Corsair (or are fine with not being able to edit RGB settings). I have a Logitech G502X without RGB because of all the headaches I was having with my last few Razer and Corsair mice.

Edit: OpenRGB is another resource if you have an RGB device and need to change some settings, there's a list of supported devices on the website.