Organisers of the protests estimated that there were 1,4 million participants in Germany over the weekend.[1] German police had a more conservative estimate of 900k participants.[2]
In the city where I'm staying (Cologne) 80k people showed up. That's almost one in ten for a city of a million. That is impressive.
It's easy to say these numbers are not large enough for a country of 83 million. What has to be taken into account, is that it happened all in a matter of a week and nationwide. These were not protests that were advertised and organised long before.
[1] https://www.zeit.de/gesellschaft/2024-01/muenchner-demo-gege...
[2] https://www.zeit.de/politik/deutschland/2024-01/proteste-rec...