https://www.prepaidphonenews.com/2018/01/opensignal-t-mobile-is-leading-carrier.html
Poor Sprint, just can't seem to catch a break.
With the right phone (which I don't have) a buddy of mine got 188Mbps on the Sprint 4G+ network. I think it he said it uses 3 connections at once to get those speeds.
Your friend was likely referring to carrier aggregation.