A heads up to folks thinking of getting the Gog version of Skyrim SE, is that you will have issues with some SKSE-based mods.
Here are the particulars. The short answer is that SKSE mods that have a .dll file will not work on the Gog version of the game. However SkyUI is not one of those, so it works with the Gog version. It really is a very small proportion of mods. But you might look into that before you buy.
It does appear that authors are updating their SKSE mods to be compatible however. Which ones and how soon, if at all, is naturally going to vary of course.