The thing is: even if your company is abroad, if you live in Germany then that constitutes "Permanent Establishment". So that means that Germany considers that the company is in its own juridiction so german laws would apply.

This also should be true about the holding (although I am not sure). You cannot simply have a German holding which contains foreign operating companies and not get involved with German bureaucracy. Logically you should report operations of those foreign companies (thus declaring taxes) in Germany. That would be an even more painful headache ...