I should have been clear about which resistor. I was talking about R18 as current limiter to the presumed load on the header. That way if the header gets shorted or the load has too high a draw at 3V3 you don’t blow the transistor.

R20 is probably a weak pull down resistor to keep the transistor off until the microcontroller comes online.

As far as the transistor I was thinking it was probably a 2N7000. That’s my goto in this kind of circuit.

Depending on the spefic microcontroller the pins can default to a very week high even when off. Enough to activate a 2N7000. I’ve had motors briefly engage using a PIC and a 2N7000 when the system is turned on without a pull down resistor.