Building a PC right now is not the best idea, RAM and storage prices have increased a lot (in the US) anyway. And I agree with the comment that pretty built aren't the best option either. My friends who have got pre Built's have both had issues with them. Alternatively, steam just announced their new steam machine which will be based on their steam OS and I believe will have a normal linux desktop environment like the steam deck does. As for distro, I use and recommend linux mint. It's designed very similar to windows and you don't need to access the terminal as often as some other distros. I have an Nvidia 4070 and it works perfectly fine with mint.