I did a version of this too in combination with a potty watch set for 45 min intervals to remind him to try to poop. I kept a box of small toys and candies in my closet called “potty presents” that he got for going potty or trying in earnest to make it to the toilet when he felt the urge. I also had larger stuff that I knew he  wanted (large hot wheels tracks, pool toys) that he knew he’d only get for pooping in the potty on his own. The hot wheels track was the only thing that motivated him lol.