Yes, You can use XiaoMi Redmi 8A (model: M1908C3KH) in the USA.
The XiaoMi Redmi 8A with the model number M1908C3KH supports 4G LTE Bands: B1, B2, B3, B4, B5, B7, B8, B20, B28, B38, and B40.
It also supports 2G GSM 850/900, 1800/1900.
In the U.S. AT&T’s 4G network uses Band 17(700Mhz), Band 5(850Mhz), Band 2(1900Mhz) and Band 4(1700/2100Mhz).
The Redmi 8A (model: M1908C3KH) is compatible with AT&T’s network.
So you can use Xiaomi Redmi 8A M1908C3KH in the USA with AT&T’s tower.