Using ATSamD51 to flash ESP32

[BillBB]

Hi,
I'm building a device that uses an ARM ATSamD51 mcu with Adafruits Metro M4 bootloader so it works with Arduino but I am also planning on using the ESP32 to ptrovide WiFi or Bluetooth connectivity. I want to be able to reprogramme the ESP32 as well as the D51, and ideally to do it using the D51 USB interface. I imagine this would be possible by loading a sketch into the D51 that resets the ESP32 into bootloader mde (with a couple of pins pulled to the correct state) and then copies USB data over to the ESP32 UART and back. I could then use the Arduino IDE to flash the ESP32? ... Does anyone know if this will work or am I missing some important details?