I think you’re underselling Darktable somewhat. Being able to use drawn and parametric masks for basically all the tools, and the granularity at which you can adjust the variables across the entire image makes it incredibly powerful for non-destructive editing of photos. There are also numerous filters and tools which can be used artistically.
But yes, for “photo-shopping” as opposed to photo editing you probably will want GIMP as well.
Best in Scotland and the Lake District