Well, I find Gimp unusable because I learned PS hotkeys 15 years ago and whenever I press them in Gimp it does random things. Photopea is nearly a 1:1 mapping of PS. Can't comment too much on feature parity, I don't do anything too crazy. Some cropping, expanding canvas size, maybe desaturate or adjust levels, use layers and masking. Magic selection. Maybe some content-aware fill. No artist/painting/fancy brushstroke stuff though.