An USB isolator will help eliminate ground loops and cuts down electromagnetic interference (EMI) among the pc and also the linked device. 1x GND 3V3 (P2 with 2 pins two.54mm) connector can be used to electrical power externally the WCH CH569 MCU (it is recommended to remove the P4/SHUNT in that scenario it is not necessary as being the 3V3 LDO