In my app, I use CoreSpotlight to create CSSearchableItems (for Spotlight integration), and I also have a list of AppEntities for Shortcuts support. Are there any big benefits in migrating this setup to using IndexedEntity, with regards to Siri and Apple Intelligence? I also would need to support iOS17 for now. Note that the AppEntities don't map onto any existing AppSchema domains.
IndexedEntity is available starting iOS 18. Siri interacting with your entities requires that they be schematized and fit into one of the existing domains. In your case, you won't see behavior changes by switching from using CSSearchableItem directly to adopting IndexedEntity since your entities are not schematized and are accessible in the Spotlight UI but not via Siri.