Secrets Sync with GitHub Enterprise

I am trying to configure the Hashicorp Vault Enterprise Secrets Sync functionality with a GitHub Enterprise instance. However, I do not see a field to configure the base URL of GitHub. It seems to default to github.com, or that’s the only possibility right now. The destination endpoint /sys/sync/destinations/gh/:name does not seem to have an option for overriding the GitHub URL. I thought I could use a GitHub App, but that endpoint sys/sync/github-apps/:name in Vault also doesn’t appear to let us set the GitHub URL.

Do these two endpoint look correct, or am I overlooking another API endpoint or method of enabling secrets sync to a GitHub Enterprise instance? Or is this not supported?