KDE also has @digikam (photo manager), which has an editor called Showfoto that's similar to Darktable. It can also be run on its own. Been using it as the default image viewer and editor for years and it's quite good.
KDE has so much potential to create an open-source counterpart to the Creative Suite, due to the sheer variety of creative software and integrations they have with each other. A big reason why people use Adobe apps is that they fit together, making for extremely efficient workflows.