@Deez Thank you for your suggestions. After playing around a little bit I have noticed that the current implementation of the Lock Template fulfills my needs. The Lock entity reads the lock-state from KNX-Sensor and uses the lock and unlock with the KNX-send commands.
For others who read this thread: If you have set up the lock template and you want to bring it to HomeKit, you need to exclude the lock-entity from default bridge and then you need to add a second HomeKit-Integration with Accessory mode => scan the QR-Code under new discovered devices with the Home-App.
For the Open/Closed state I’m using a simple binary sensor.
@MarfMcScott I hope this helps you too.