Someone ( on /b/ I think ) recommended Photoscape X. I think it was more a Photo graphics package rather than a photo to artwork AI application though.
I tried it and converted the upper image of Greta Thunberg (that happened to be doing the rounds at the time) into the lower image.
After "getting my bearings" in the application it took me about 30 seconds to turn the upper image into the lower image - wasn't even much of a learning curve really, although I am already quite competent in using GIMP and used Adobe Photo Deluxe for many years, so I knew what I was likely to be able to do with it.> pic related
looks like it might be good and theier "gallery is very impressive:https://fotosketcher.com/fotosketcher-gallery/
but I haven't tried it, so I can't say anything about how easy it is to use.