Same, since i switched over to linux 3 years ago I have been using GIMP I also use RawTherapee which is a great program considering its open source, but it is nice if you can get a perfect shot, but it is not always possible to get that perfect shot every time.
I have a Nikon D5600 myself and a few lenses.
Its funny the first thread I start on a science forum turns into a discussion on photography, mind you I suppose the two subjects are related in many ways, optics, chemistry, electronics etc.