I would also recommend against using Brave, but it’s available on Linux if you want to use it.
Pirated games work just fine with Heroic, Lutris or Bottles.I personally like Heroic and I’ve not had many issues with steamrip releases (they don’t need to be installed).
I have a 2015 with R9 M370X, tried Ubuntu and Arch. The latter worked better out of the box (wi-fi, bluetooth, trackpad, etc. minus webcam) for me so that’s what I’d recommend (with archinstall).
You should be able to use gpu-switch to enable or disable discrete graphics: https://github.com/0xbb/gpu-switch
In the end I gave up on trying to run Linux on my specific MacBook. With amdgpu, it would seemingly run fine. Watching videos on Youtube, even with H264ify, the temps would slowly creep up over 90c. I had to bump up the fans quite high with mbpfan. However, the biggest problem was that it would randomly lock up after 20-30 mins of continuous general use.
With Intel Iris graphics, even general browsing with firefox was too annoying for me. Even continuously scrolling basic webpages would raise my CPU temps to around 90c with the fans blasting. It ran fine otherwise, no kernel panics or anything. Just too noisy and hot for my liking.
What kind of cooling do you have? Do your fans actually run? Like do they ramp up when your CPU is hitting 100+?
Probably worth changing your thermal paste, slightly excessive paste is better than too little paste. Whilst there, make sure you’ve removed the film from the CPU cooler and make sure it’s seated properly.
Go into your bios and adjust your fan curve for CPU, whilst you’re there turn off zero RPM or adjust its temperature so that the fans turn on sooner. Use something like LACT do the same for your GPU.
Your idle temps aren’t too bad but something isn’t right if you’re hitting 100C+ at load. Especially on that CPU.