It happening to support a band or two used in NYC doesn't tell us much - we need to know all the cellular bands it supports, because even a 6 year old iphone doesn't support bands used in a lot of areas. Cell companies are now focused on 5G and a phone that doesn't support most US 4G frequencies, and 5G, is going to be increasingly hobbled.

Edit:

https://www.devicespecifications.com/en/model/344c59bb

Supports no UTMS (3G) bands, ten LTE bands and no 5G bands.

LTE-FDD 850 MHz (B5) LTE-FDD 900 MHz (B8) LTE-FDD 1700 MHz (B4) LTE-FDD 1800 MHz (B3) LTE-FDD 2100 MHz (B1) LTE-FDD 2600 MHz (B7) LTE-TDD 1900 MHz (B39) LTE-TDD 2300 MHz (B40) LTE-TDD 2500 MHz (B41) LTE-TDD 2600 MHz (B38)

An iPhone 8, six years old, supports twenty five LTE bands.

According to Tmobile's website, they use the following bands:

4G LTE

    Band 2 (1900 MHz)
    Band 5 (850 MHz)
    Band 4 (1700/2100 MHz)
    Band 66 (Extension of band 4 on 1700/2100 MHz).

Extended Range 4G LTE

    Band 12 (700 MHz)
    Band 71 (600 MHz)

...and then the 5G/5GUC bands.

So the overlap would be B5, B1/B4, B39. No support for 5G. No support for UTMS, band 66 or extended range...so good luck using it in rural areas.