I found this very comprehensive guide about freelance visa in Germany:
https://allaboutberlin.com/guides/how-to-get-a-german-freelance-visa
Does anyone of you know if I can travel Schengen with that visa or is it only a national visa? If I can travel with that visa in Schengen, are there any requirements to not leave Germany more than x days?
I know within Europe there are no border controls so any time abroad would be hard to track in most cases anyway.