Both AT&T and Verizon are in the (very) early stages of rolling out their 5G networks, but T-Mobile is taking a while longer to get everything in order. The carrier hasn't begun to officially market its 5G network, but one person in New York was able to give it a shot using an unlocked Verizon Galaxy S10 5G — and initial results aren't bad at all.
Milan Milanović was seemingly able to connect to T-Mobile's under-development 5G network using an unlocked Verizon Galaxy S10 5G, and was able to reach download speeds of nearly 500Mbps. That can't quite match the gigbait speeds seen on AT&T and Verizon's networks, but if T-Mobile's 5G support is "blanketing" Manhattan as Milanović said, that certainly makes it more practical than other current 5G networks — which have an extremely limited distance.
We'll have to wait for T-Mobile's official 5G rollout to see how the network performs with thousands (or millions) of people using it at once, but this is a promising start.
more here:
https://www.androidpolice.com/2019/05/28/tester-sneaks-on-to-t-mobiles-5g-network-in-manhattan-pulls-down-500mbps-downloads/