Hitachi Cassette Air Conditioner

I’ve got a Hitachi Cassette AC with this controller, I’ve been wanting to integrate it into Home Assistant.

The controller doesn’t have Wi-Fi.

What can I do to get it into Home Assistant?

I’m searching for a similar solution, have determined that the controller needs to be replaced/ upgraded if you want HA integration. A workaround noted here https://whrl.pl/Rgjl3v to wire in a relay to the controller at least would give on/off control via wifi.

To complete this post, the only workaround for wifi control of older Hitachi/ Temperzone wall controllers is to connect a Shelly relay to the pcb, details my hack here: https://whrl.pl/RgI2bq

Quite bold claim. May be easiest though.
I’m sure you can do it with any dry contact smart switch, with bare Esp-board and relay or even with Esp + transistor.
There are also pins for 10kOhm remote temp sensors, one could connect it to digipot and Esp for temperature manipulation/control.