Is this progress? Cat introduction assistance

My resident cat and kitten are being introduced slowly but surely. We’ve mainly done door feeding, scent swaps, and site swaps. I’ve decided to go ahead and let Peter walk around while Milo was in her base camp. Just a moment ago, they were both playing. It took a moment, but I kept distracting them with their favorite toys until they started playing with one another. Resident cat wasn’t growling and was wiggling her butt and playing chase/being chased. If she was “swatting” at him, there were no claws and her eyes were big like they get when she plays with a toy. She later started growling again and swatting at the kitten (with claws). I’ve since separated them. They played for a little over 20 or so minutes with each other. Just curious to see if this is progress or not. I know how they both are when playing, they were definitely playing.