is there any timeline where GOG achievements are planned? The latest info I found is from end of March 2017, where it states:
The GOG version won’t have achievements, at least not on day one. We might go back and add them, but there wasn’t enough time. Other than that, they are exactly the same.
Statement by Ron Gilbert
I know, this is low priority but for DRM reasons I always prefer using GOG over Steam. I could of course replay the Steam version, but my home is GOG.
Of course I don’t know how different the API is and how much effort it is to create the achievements in the different platforms. Judging by the post about release with the different sizes for all the store front graphics it might not be that trivial.