Control thermostat with MSP430TM controller

I do not want to replace it, only extend the functionality, with keeping the original.
Its sold by a company ‘Computherm’ COMPUTHERM T32 | Computherm - Digital, Wi-fi, mechanical thermostats
Most, but probably made somewhere in China.
I’m looking for an integration, that’s why I’m here.
As I wrote it has TX RX connection points, so I believe with Serial port I could communicate with it. Problem is I do not know how. With the UART module of ESP if I’m correct.
There is a manual, not helpful for this kind of modification.