On GOG, much of the "cross platform" support is using Wine emulation and Boxer for the OS X and Linux game support . DOSbox is used for DOS support under Windows (I use DOSbox SVN-Daum myself under Win10x64.)
Whatever Larian used to build the Linux port for Divinity Original Sin, it works great.
My opinion is that if you like gaming enough to buy several games a year and play them then you definitely want to be on Windows--as well, you can dual-boot Windows natively on a Mac and Linux x86 PC, and so...it's not much of a problem.
You have to manage (and pay for) a complete additional operating system. The update process alone is a torture. I also need my Linux system online, also when playing in between.
I think creating an involved, complex game on Win32/x64 D3d/OpenGL/Vulkan (although the latter API is rather slowly growing) is enough of a job for any major developer--paying other companies to port the Windows version to other platforms later is not without its own set of problems--and extra expense.
I think Larian has already done a lot of this work, because they have ported the first part.
If you like games it seems foolish to punish yourself on a secondary gaming platform--just imo...;)
It's a matter of opinion. If it doesn't appear for Linux, I'll buy it for my PS4 as soon as it appears. I would rather play it on my Linux-PC. I'd buy more than one copy for Linux. Divinity Original Sin I often gave away. Co-op is big fun.
But let's see. I think Larian is very busy right now. Linux is only a small ecosystem with few users. If it's ported, it certainly won't be this year. I can wait.
