[AshamedCaptain]

You don't even need containers. These techniques (a chroot + static qemu-user with binfmt) were used many years ago to cross-build (and test) entire distributions for exotic architectures.

I remember http://scratchbox.org/ would allow you to replace some components (e.g. gcc) with their native versions so as to speedup them. It is all hopelessly broken now.

[fargle]

Certainly! It's just that you might want separate mount, network, etc. namespaces. Hence: "the next step"

With a little work you should be able to do this as unprivileged/rootless as well.

[seba_dos1]

I'm still using Scratchbox (inside Docker) to build games for Maemo 5 (Nokia N900), as that's one of my engine's supported platforms ;)