Trying to flash ESPHome on Sonoff 3-way switch T2EU3C-RF


i bought the Sonoff 3-way switch T2EU3C-RF (link to and I tried to find out how i can flash ESPHome on it. The suggestion is always to use the serial port - but the hardware I am presented with, has got only I²C (3V3, SDA, SCL, GND).

I would love to get some suggestions on how I could proceed with the matter.
Thanks in advance :slight_smile:

Aren’t the tx, rx ports already labeled on the pcb?
Do you have any pictures?

Isn’t that a 433MHz device? You don’t program it, you use an RF Bridge.