Register Qemu as PowerPC LE binary handler. This leverages binfmt_misc capability of the Linux kernel and is the key thing. More details on binfmt_misc is available here
Check the host CPU architecture.
The command below will register interpreters to run binaries belonging to specific architecture.
docker run --rm --privileged multiarch/qemu-user-static:register
Any ppc64le binary (magic - 7f454c460....) will be executed with /usr/bin/qemu-ppc64le-static.