Thanks to the fork mizuyoukan-ao created, I was able to backport their fixes into here to return functionality for Firmware 12.0.0 and newer!
Flash to your ESP32 with the command esptool.py write_flash 0x0 NAME
ESP32 binaries compiled to portable binaries with: https://github.com/vtunr/esp32_binary_merger
Flash to your AVR with AVRDude, or however you like. :)