Depending on the Modules it's desired to directly strap USB D+/D- to the Module (eg ATSAMD21 or ESP32-S2) or to strap USB to a USB/TTL Chip (eg CP2102N) and send RX/TX to the Module.

Luckily i included a USB Mux chip on the Reference Base Board. The Module can tell the Mux (by pulling a pin high or low) to send Dp/Dn directly to the module or to the on-base USB/TTL Chip.