RAK3172 different frequency band same module?

Could anybody tell me if is possible to use RAK3172 EU868 for US915 using custom firmware. Is any hardware limitation? I am asking this because I want to test both EU868 and US915 variants, do I need to buy two modules, or I can buy only one and modify only in firmware?
Thank you

From hardware side a RAK3172 can be used for IN865, EU868, AU915, US915, KR920, RU864, and AS923-1/2/3/4 or in LoRa P2P from 863MHz to 928 MHz
But you need to use a matching antenna or a wide band antenna.

From firmware side, our standard AT command firmware or a custom firmware based on RUI3 API does support the same LoRaWAN regions or in LoRa P2P from 863MHz to 928 MHz with AT commands or API calls.

The only frequencies that require a different module are EU433 and CN470. These lower frequencies require the RAK3172(L) which has a different RF path tuning.

Ok, thank you. Now is clear.