On Steam this game has both a Mac and Linux version that run great, why not include them here as well?

Because Feral Interactive has the licence to those ports and refuses to release them DRM-free here. Same with Tomb Raider: Definitive Edition, Alien Isolation, XCOM Enemy Unknown, XCOM 2, et al.

As someone wanting to move to Linux soon, I'm interested to hear how this Windows version of the game on GOG works with Wine.

I just tried it with vanilla wine staging version 7.17, and it works flawlessly for me. dxvk (installed through winetricks for me) obviously does have a hugely beneficial impact on performance, but even without I found the game to run adequately. No crashes, corruptions or anything else in several hours of gameplay. (edit: 1 crash after 10+ hours of gameplay.)
appdb and protondb both give it a gold rating, too.