After successfully completing several tours through Nepal, and with all participants obtaining their visa following the procedure described on the website of the Honorary Consulate General of Nepal in Cologne, I would like to once again refer to that site. It clearly explains how to apply for an electronic visa or ETA (Electronic Travel Authorization).
Here’s the link: https://konsulatnepal.de/visum-beantragen/
I haven’t read anything positive about the Visa on Arrival option, and several sources advise against it, as the process at the airport can be very time-consuming. You should expect at least two hours of waiting. It’s therefore advisable to get the visa in advance.
If you'd still prefer to go through the official website of the Nepalese embassy in Berlin yourself, here’s the link:
Alternatively, you can make things easier by using a visa service. Just make sure to allow a little more time for processing.