Nodemcu v3 - Power supply via VU pin?
The circuit diagram of a NodeMCU shows that there's a schottky diode between Vusb (the voltage input supplied by USB) and the Vin pin. This has the effect of reducing the approximate 5V voltage supplied by your typical USB jack/outlet/cable to something slightly lower. In my case, the apple USB charger adapter provides 5.1V but this gets reduced to 4.76V on the Vin pin. This Vin voltage is also quite noisy. I don't know if that will affect your servos. I've run one NodeMCU from the Vin pin of another NodeMCU pin without any trouble.
The schottky diode in the NodeMCU is a 1n5819/SS14/S4(SOD_323). I'm not certain, but if this is the correct datasheet, it says it can supply 1 amp, which sounds like enough. If I were you, I'd try and see if I could get power directly from the USB source rather than taking it off the NodeMCU pin. It might work off the pin, though. Try and make sure you get a USB that supplies at least 5.1V, though. It's going to be close.
EDIT: I would also add that the NodeMCU will be drawing power, too. If you are drawing 300mA with your servos and 100-150mA with your nodeMCU, that's cutting it pretty close for most USB power sources. A Macbook, for example, can only supply 500mA via a USB port. This article says a NodeMCU can consume up to 400mA under some circumstances.
Generally speaking, I've been told that it's a bad idea to use GPIO pins to drive anything that draws a significant amount of power. I'm thinking you should maybe consider using some kind of servo driver or relay or something.