@dansup But, you don't need a centralized service to seed new Loops servers. This just sounds like Bluesky's starter packs (https://bsky.social/about/blog/06-26-2024-starter-packs), but instead of it being per-user, it's per-instance.
You feed your instance a list of post URLs from whatever Fedi instances you want, and that's what the user will see when loading Loops. Don't want to use post URLs? Use account URLs. Simple, easy, without a need for centralization. You could even make these lists shareable using categories to help other instances subscribe to them. Again, all federated.