Sad to see this has not been answered by Sonatype.
I have the same question.
From the Nexus UI it does not look like it supports multi-arch docker images.
I really hope I am wrong. If not I hope it will come soon (Even if it will be PRO only).
We have need to have a docker image for jdk11 both for Linux, Mac and Windows.
I do not want to create different docker image names for each arch.
I order to build multi-arch it looks like one need to active the docker experimental features.