According to the manufacturer's website, Tado-x works with the Thread wireless standard and the Matter communication protocol. So, contrary to the previous answer, it does not necessarily require a Tado-Brdige, but a border router.

The tado° Smart Radiator Thermostat X operates using a proprietary communication protocol on the 868 MHz frequency (6LoWPAN), not Zigbee or Z-Wave. It connects to the tado° Internet Bridge for internet connectivity and smart home integration​.