LoRa US Bands & Subbands

US LoRaWAN frequency spectrum has 64 uplink channels available (125 kHz each) (channels 0-63) starting at 902.3 MHz which increment every 200 kHz up to 914.9 MHz.

There are 8 additional uplink channels (500 kHz each) (channels 64-71) from 903 MHz which increment every 1.6 MHz up to 914.2 MHz.

For gateway to end-node device communication, there are 8 downlink channels (500 kHz each) (channels 0-7) from 923.3 MHz which increment every 600 kHz up to 927.5 MHz.

LoRaWAN Channels, Frequencies & Sub-bands
Frequency bands Frequency range (MHz) Channels
Total USA band 902.3 - 914.9 0-63
Uplink sub-bands Frequency range (MHz) Channels
Sub-Band 2 903.9 - 905.3 8-15
Downlink sub-bands Frequency range (MHz) Channels
Downlink sub-band 903 - 914.2 64-71

condensed from LoRaWAN USA frequencies, channels and sub-bands for IoT devices

Typically when ordering LoRa devices you only have to specify the frequency band, US915 for US devices, but you may be asked which sub-band you would prefer.

From all my research, your best option in the US is going to be:
Sub-Band: 2
Frequencies: 903.9 - 905.3
Channels: 8-15