Any attempt to use GnuPG to automatically extract the wkd hash form of a given User ID seems fraught:
- if you use --list-keys --with-colons with --with-wkd-hash, there is no change
- if you don't use --with-colons then you're in some sort of non-machine-readable not-an-API space, which is likely to break on upgrade.
This suggests that people have no way to use gpg itself to generate the expected output in an automated way.