While working on cross-related PRs I came across emulators introduced by 9c8fd41. They seem useful but haven't been documented anywhere. IMO would be a good addition to the cross-compilation section of the manual once #105364 is merged.

As I understand it, some use cases include

• testing cross-built binaries
• allowing cross-building of some packages (especially some compilers and tools) that use cross-compiled binaries at build time

Pinging (author of emulators feature) @matthewbauer, (cross infra maintainer) @Ericson2314