This is something I can work with, but at the moment it seems time is needed to research hubduino. Being through spotlighting a few terms in the hubuino link it is clear that no other boards eg; Mega, Nano etc have yet to be implemented as the main connection. So is it possible to interace from a mega then ESP or does it have to originate from the ESP as the main board?
Hopefully tomorrow there will be some off these in hand to start the process.
Editting note. Its been a few years since hubduino was first released. Gosh this is going to be fun if I can get the stuff im imagining to work. It will be a few days before the hubitat comes in.
HubDuino supports many hardware configurations, as listed in its ReadMe on GitHub.
Turn your Arduino UNO/MEGA/MKR1000/MKR1010/NANO33IoT, ESP8266, or ESP32 into Anything you can imagine! HubDuino/ST_Anything is an Arduino library, sketch, and Device Handlers that works with your hardware to create an all-in-one SmartThings device.
Arduino with SmartThings ThingShield (ThingShield no longer sold)
Arduino with W5100 Ethernet shield
Arduino with W5500 Ethernet shield
Arduino with WiFi101 Shield (or Adafruit ATWINC1500 module)
Arduino MKR1000 (has integrated WiFi101)
Arduino MKR1010 (has integrated WiFiNINA)
Arduino NANO33IoT (has integrated WiFiNINA)
Arduino with ESP-01 for WiFi (Warning: This has never worked all that reliably)
Standalone NodeMCU v1.0 ESP8266-12e
Standalone ESP-01 (or really any ESP8266 based board)
Standalone ESP32 board
Hope this helps explain it a little more.
These days, the simplest solution is to use an ESP8266 or ESP32 based microcontroller. Both are very robust and reliable.
If you have any questions or issues with the Nano 33 IOT, let me know. I can pull mine out of the drawer, dust it off, and make sure everything still behaves as expected. It has been a few years since I have fired that little board up! A lot of things have changed with the Arduino IDE during those years.