Powering Argon or Photon2 with 3.3V Supply

Is there a way to power the Argon with an external regulated 3.3V supply (up to 500mA)? I am trying to power the Argon off of a different board with a 3.3V output supply. Otherwise I would power the board with ~5.0V on VUSB.

It looks like powering the Argon through the 3.3V pin while disabling the regulator is not a reliable option. Could I power the VUSB pin with 3.3V, or does the regulator require a voltage higher than 3.3V for the Argon's modules to function? The datasheet for the XC9258A regulator says than the minimum value for Vin is 2.5V.

Lastly, would the answer to this question also apply to the Photon2?

You cannot power the Argon, Boron or Photon 2 by 3V3.

This pin is the output of the on board 3.3V step-down switching regulator (Torex XC9258A). The regulator is rated at 1000mA max. When using this pin to power other devices or peripherals remember to budget in the current requirement of the Argon first. Unlike the Photon, this pin CANNOT be used to power the Argon.

The only way to power Feather devices is via the Micro USB, VUSB, JST battery connector, or LI+.

We recommend supplying VUSB at 5V for compatibility with other Feather accessories, however if you are not using FeatherWings that use VUSB as a 5V supply, you do have some ability to supply a lower voltage, down to around 3.6 VDC.

If you really need to use only 3.3V, you should use the P2 module, which does not have an onboard regulator and is intended to be supplied with regulated 3.3V at 500 mA.