The biggest issue I had migrating as a Photoshop user since 1996 was the key bindings. But using the config files people shared online sorted that.

I'm not going to link to a specific one implying I'm recommending it, but a web search will show multiple.

One important gimp note is if you don't have 3.0+ already, get it. It finally has non-destructive editing, which is the main reason I had to keep using ps for for a long time.