How to migrate a startup volume from an Intel to an M1 Mac

Apple chose a different startup scheme for its Apple silicon models that prevents booting up from an Intel-targeted disk.

After purchasing an Apple silicon M1-based Mac, people have discovered that an external startup volume used with an Intel Mac won't boot the newer computer. Apple has organized hidden partitions that are part of the startup process differently for macOS volumes that handle Intel and M1 Macs. As far as anyone understands and has attempted, you can't make a dual Intel/M1 bootable startup drive. (If you know otherwise, let us know.)