Hi!
I understand why you might want to move away from Photoshop, it's not like the subscription model has made Photoshop any better, quite the contrary if you ask me. However, I'm afraid we don't have plans to do an export script for Corel Painter.
I would suggest taking a look at Affinity Designer. It's a great alternative to Photoshop, I'm considering making the change myself. Affinity Designer used to have a Spine export option, but I'm not sure if that's still a thing.
