Relays choose which PDSs to index. I think there's some way for independent PDSs to send an HTTP request to a specific relay and be like "yo pls index me" but I don't know if it's roadmap or live. Anyway the relay could always ignore that.

For pushing nostr content into Bluesky, something tells me the Bluesky team trusts Bridgy Fed more than Alex Gleason Inc.

I guess if Alex made his own AppView and spun up one of these budget relays he could use that AppView to hydrate whatever content and relationships from whatever PDSs he wanted (bsky.app hosted or nostr bridged/programatically controlled) and keep track of timelines and all. But then you'd need his client to see the combined universe. And PDSs would be outside hosted.

On the topic of Bridgy Fed though, here's the Bridgy Fed guy's talk from the ATProto conference a few weeks back. I think he likes nostr, cause at the end of the talk he talks up nostr as some sort of destination where things are converging or something. Watch to the end. Maybe he's a sleeper agent for you.