I might have adjusted the container to run with my local DNS, but all I'm doing for that service is:

   - Pi-Hole- Hostname:
       icon: /icons/pihole.png
       href: https://my.internal.domain/admin
       server: Hostname
       widget:
          type: pihole
          url: https://my.internal.domain/
          version: 6 # required if running v6 or higher, defaults to 5
          # Application Password:
          key: "<< REDACTED >>"

Replaced my Pi's hostname, internal domain, keys, etc, but I have this running for two Pi-Holes on my network.