I'm so close to dumping windows and my final concern is gpu and multi monitor support. I only ever run linux on servers or VMs, so no real experience on bare metal.
About high refresh rate games: I have gamed on 144hz/120hz (one gaming monitor and another OLED TV) but I prefer to lower it so I can increase quality of graphics.
Multi monitor I can't say I have much experience with them connected at the same time but I have used the OLED+Gaming monitor few times but I can't say I do it often.
What I do very often is to leave the machine running and use RDP/Steam client to connect to it and game/work.
Linux support, and Ubuntu and Gnome for that matter, improved leaps and bounds since last LTS.
Dual monitors will work well if they're similar, but I wouldn't mix hi-dpi with low-dpi or different refresh rates. I've heard most of that doesn't work or is poorly supported.