These relay boards can be bought on eBay.
They use an ESP-01 (ESP8266) wi-fi module to control the relay.
The original way to control the relay is by using serial commands:
Open: 0xA0, 0x01, 0x00, 0xA1
Close: 0xA0, 0x01, 0x01, 0xA2
They also need need configuration via the serial 4 pin header.
Then the ESP-01 board sends those commands to the 8-pin micro which controls the relay.
With suitable code, the ESP-01 module could control the relay directly.
Remove the 8-pin micro-controller.
Link pin 3 (GPIO2) of the ESP-01 module to pin 7 of the (now empty) micro-controller.
The ESP-01 can now activate the relay by setting GPIO2 high.
To be continued …