There's no question that his physical attributes are not on the level of ZW. I've watched a lot of 49ers football, and have a hard time seeing Purdy as anything but a system QB.
If ZW's decisionmaking could have benefited from years of Shanahan coaching and a great system, I think he would be less INT prone as well.
But, at the end of the day, is this even a conversation worth having? There aren't many QBs in the NFL that wouldn't benefit from a great OL, a strong run game, and weapons like Kittle, Samuel, and Aiyuk.