Here in India my iPhone 13 has delivered me gigabit speeds. And it's not just me my friends also get those speeds at times (early morning usually when networks aren't busy). So the iPhone supports well over gigabit speeds on 5G already. That being said during day time I have seen speeds below 10mbps on 5G so it is very traffic dependent and has nothing to do with the pro being more capable so its faster.

Edit: Apparently if you are farther the Pro is better. Could be interesting but if the tower is bogged down with traffic it won't help anyway in my case.