Comment by benou

Here is an example of preparing a debian ARM image on x86 with debootstrap, qemu and chroot:

  ~# sudo apt install qemu-user-static debootstrap
  ~# mkdir /tmp/arm
  ~# debootstrap --foreign --arch=armhf buster /tmp/arm http://deb.debian.org/debian
  ~# cp /usr/bin/qemu-arm-static /tmp/arm/usr/bin/
  ~# chroot /tmp/arm   # from that point, you're running ARM!
  ~# /debootstrap/debootstrap --second-stage