Over 30 networks are actively selling 5G to consumers. About as many more carriers have told the press they are active but are really still in trials. T-Mobile US has a low-band offering it considers 5G but is slower than most 4G. I think that's a scam and don't include it.
The latest live list is here. Below, the list from Dec 26, 2019
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License.