Docker apparently makes use of a Linux feature that can hand other-arch binaries off to another application to deal with. This post on the Docker blog explains

Docker apparently makes use of a Linux feature that can hand other-arch binaries off to another application to deal with. This post on the Docker blog explains it generally: https://www.docker.com/blog/multi-platform-docker-builds/ https://www.docker.com/blog/multi-platform-docker-builds/