Hi folks, I noticed that there weren't any commercial available HDMI-switches which worked with home automation software, that's why I chose to built one myself.
The base of the switch consists of a cheap 4k HDMI-switch with an IR remote. With the help of an IR receiver I recorded the codes and saved them as hexadecimal codes. After that, I chose a microcontroller to use with the project: an esp32-s2. I wrote a little program using the arduino library HomeSpan to send the codes with an IR led to the HDMI-switch. Now I can control my HDMI source device through homekit!