Just wanted to check if the USB host stack available in MCUXpresso SDK supports 4G modem type devices. Also SFTP protocol as i don't see any SFTP protocol in lwip stack in the SDK.
The SFTP protocol is not supported. As for the 4G modem type devices, I believe it depend on the USB class type required for your modem. As long as it is a supported class, it should be OK.