I have a 5v power supply powering my project. If I connect VUSB to the power supply, is it safe to connect the ESP32 Thing Plus to a computer via the micro USB port at the same time? If not, would connecting a regulated 3.3v power supply be an alternative solution? I need to be able to program the board, while having the board powered up via external power supply.
Your computer might not be happy with 5 volts showing up unexpectedly on the USB port, but I don’t see anything on the board that would care. As long as your computer is happy with that, I think you’re probably OK.