If I’d have an (Electron) app that produces a certain kind of artefacts, let’s say planet photo galleries, and adds them by using Helia: How can a peer find all available photo galleries produced by that app (by other peers) ?
A peer can choose to like some of those images, and pins them to IPFS by doing so. Maybe the same question: How can peers find available photos that have been liked?
You could implement one or more custom protocols that lets users of your app:
Exchange lists of photo gallery CIDs or IPNS names (better, since they can update them without having to contact your peer again)
Exchange activity logs (e.g. who liked what)
Discover other peers that support your app’s protocol(s)
A peer needs a way to bootstrap into this network, so you might stand up some servers that speak your protocol and configure your app to connect to them on startup using the @libp2p/bootstrap module, then they can start to discover other peers using your protocol’s peer exchange (point 3 above).