Fi is cool, I used them for about a year.

The only issue with MVNO’s is they get the slowest data (lowest priority) on whomever’s tower they are using. Even at full speed, often it won’t be subscription speeds.

On TMo, with Magenta Max, I get unlimited data (truly unlimited) and get speeds in the 800mbps range on 5GUC (Ultra Capacity). On lower signal it’s comparable to AT&T’s 5G, but without the cap.