Not really both Krita and GIMP works mainly on raster images like Photoshop. Illustator is a vector graphic software. The closest foss relative of which would be Inkscape.
The thing is, Photoshop was born as a photo manipulation tool but the drawing functionality has become an industry standard (I think mostly because they give free licenses to students). GIMP is a photo manipulation tool and Krita is a digital painting software. They have overlap but neither of them aim at replacing Photoshop as a whole. GIMP may be the closest match. Krita is more comparable to ClipStudio or Corel painter imo.
I'm loving the experience, but fuck me some bosses are a pain in the ass. I'm stuck on the sea spider, does anyone have suggestions?