GIMP - is a free open source image processor software. It's interface is very "photoshop-like."
Affinity Photo is a relatively new image processing suite that reviewers are rating highly. Purchase cost is about $65.
https://affinity.serif.com/en-gb/photo/
I have tried GIMP, haven't tried Affinity. GIMP works OK, couldn't rate it better than Photoshop.
Because I have always had Photoshop, I'm sure there is bias i any comparison I make. I only briefly trialed GIMP to be able to tell my students about its performance. I have been using Photoshop since 1992 and taught Photoshop workshops since 2002 so it's hard for me to rate a new product that I am unfamiliar with as better than something I've been using for 23 years. I am sure that once you get used to these products, they will work very well.
Joe