Gentoo ebuild USE and CFLAGS flags allow the user to specify custom compilation settings as necessary for optimization on a given processor architecture like i386, i486, i586, or i686.

For example, with ebuild (or dpkg-repack or rpmrebuild) a person could build the compiler packages with all of the appropriate optimization flags for the chipset on the box where the package will be installed: https://packages.gentoo.org/useflags/custom-cflags

Cross-compilation is easier with clean build containers.

With distrobox (and qemu, qemu-user-static, and binfmt-support) https://github.com/89luca89/distrobox/blob/main/docs/useful_... :

  $ uname -m
  x86_64
  $ distrobox create -i aarch64/fedora -n fedora-arm64
  $ distrobox enter fedora-arm64
  user@fedora-arm64:$ uname -m
  aarch64