From what I know docker buildx build --push will overwrite existing image architectures with the one you specified in --platform parameter. As I understand you have to build and push for all architectures at the same time when using buildx. However, I know that official docker images use arm64 build farm to build linux/arm64 images. How is it possible? Do they just use docker push without buildx? If so, does it mean docker push doesn't overwrite existing architectures unlike buildx? What's the best way to do that if I want to build and push multiple architectures on separate machines?