I have installed the GoG version of RGO via Heroic. I'm currently using Proton-8.0, but have tried experimental as well as 7.27.
I then installed the two redistributables found in the installation folder MSVC2015 and MSVC2019 via Heroic's winetricks.
The game launcher will load, and I've deselected all visual items (see pic below). After launching the game, however, I see the "Double Damage" intro video, and the game crashes immediately afterwards.