Hi,
the Homematic sensor and actuator product line is quite comprehensive. They released a 868-MHz transceiver for the RaspberryPi (german shop) and software for ARM CPUs. There’s already a project about creating LXC containers for ARM CPUs (in german).
The RPi transceiver is connected via 3.3V UART and two 3.3V GPIO pins (BCM 18 = reset, BCM17 = enable transceiver firmware update) on the RPi. It should be quite easy to connect it to the Turris Omnia.