Sorry for asking again. Last time I setup an nginx server was 2015 and I don't know if docker was even a thing back then.
I made a new host in the default config. With you example.
The fact that my (not dockerised) nip-05 server is still working but the other page is just showing it as well tells me that I am on the right path and did not screw up anything major.
The "http2" parameter does not work for me though.
As it makes more and more fun to type words into a command line I guess I will figure it out today. Nginx manual is my lecture today.