dansup , 
You might be surprised to know that the official @pixelfed app uses several "internal" services
Here are a few examples:
https://recovery.pixelfed.org is used to help users remember their instance
https://fedidb.org is used for auth and registration
https://beagle.pixelfed.net is used for the Discovery tab, allowing the smallest or newest instance to discover new content and people
https://pixelfed.org for our homemade Android updater
- more!
We love building and innovating 🚀 ✨ 😎