This would be a nice feature, imo. I like it when binary tools provide a subcommand to print shell completion functions to stdout.

For example, see this help text from kubectl completion -h

  # Load the kubectl completion code for zsh[1] into the current shell
  source <(kubectl completion zsh)
  # Set the kubectl completion code for zsh[1] to autoload on startup
  kubectl completion zsh > "${fpath[1]}/_kubectl"

Packagers who want to deal with script files could still have access to them.

This is easiest when you use Go 1.16 or higher. Prior to Go 1.16, you need an extra build config.