These days (with recent kernels) you don't even have to copy the qemu binary into the rootfs nor use a static binary - these used to be workarounds for things that kernel now handles on its own.

This is very cool! I had no idea you could chroot into different architectures.

Well technically you can't, in the sense that chroot has no idea you're doing it... the magic of binfmt support in the kernel (setup for qemu by the post-install script for qemu-user-static I believe) basically lets you run any architecture's binary that qemu-user-* supports just by trying to execute it natively, it basically just translates the execution of "./other-arch-cmd" into "qemu-user-static ./other-arch-cmd".

Thank you. That makes sense. Even though there is a translation layer via qemu-user-static, still having the facilities to have that transparently is very fantastic. And also very fascinating and a revelation to learn about for a bearded old timer like me who has never seen it before.