According to the arduino.cc page describing the new Nano ESP32, it appears that the device requires a minimum of +5V power: "The Nano ESP32 can be powered in two ways. Firstly, you can power it via the USB port, which activates the VBUS pin as an output. Alternatively, you can supply power through the VIN pin, accepting an input voltage range of 5 to 18 Volts. "
Is there any way to power the Nano directly from a Li-poly battery, or a regulated 3.3V supply? I thought the esp32 chip itself uses 3.3V or maybe lower, but does it actually use 5V power for any reason?
You can power the ESP32 via the 3.3V pin. All other power sources are regulated down to 3.3V on the board. It is possible that other things on the board might not work correctly, though. Check the docs for possible cautions.
Hello @jbeale12. The Arduino Nano ESP32 does not use the VIN or 5V from USB for anything else but providing a stable 3.3V to the ESP32-S3. The internal voltage regulator needs at least 4.5V for that, though, so connecting a LiPo battery to VIN is definitely a no-go.
I would also recommend against powering it from +3V3. You can try disconnecting USB and VIN, and providing a stable 3.3V to the pin. However, the CPU has power spikes that draw lots of current (especially when using WiFi or Bluetooth), and the board is not designed to be powered "backwards" from a single pin, so beware of brownouts or CPU hangs.