HTC 10 devices in Germany are getting a new firmware update via O2 carrier. This is a minor update that bring software version 18.104.22.168, based on Android 7.0 Nougat but you can expect minor tweaks and enhancement in over all firmware. HTC 10 already received stock Nougat update a few months back now HTC is providing updates to make the firmware stable and bug free.
The new build 22.214.171.124 firmware for HTC 10 is live for the HTC users in Germany via OTA, so you would get an OTA alert on your device any time soon. Some time the OTA takes regional delays to reach every user in different area of country but lets tell you, that there is also a manual way through which you can call it right away, go to Settings > About device > System update.
Note: If the firmware strikes your device then we recommend you to charge it well before downloading or installing the update.