Does my app entity have to conform to an app schema, such as photos, calendar for it to work with Siri? Same for app intents and on-screen awareness

No — your app entity does not have to conform to a specific app schema like Photos or Calendar just to work with Siri.

What the WWDC sessions indicate is:

• App entities are the core way to model your app’s content.
• App schemas are what let Siri understand what kind of thing that entity is and reason about it in a system-recognized way.
• If you want Siri to understand common concepts like a calendar event, photo, message, or contact, then conforming to the relevant schema is what enables that deeper integration.

So the short version is:

• Basic entity modeling: not enough by itself for Siri to understand it fully.
• Conforming to an app schema: recommended when you want Siri to reason about that entity type.
• App intents: can be available across the system, and when they conform to schemas, Siri can understand and execute them more naturally.
• On-screen awareness: also relies on app entities to describe what’s on screen, and schemas help Siri understand those entities in context.

From Build intelligent Siri experiences with App Schemas, Apple says that once you model an entity, “on its own, that’s not enough for Siri to be able to find it or talk about it” — the entity should conform to an app schema so Siri knows what category of thing it is.

So:

• If you want Siri support in a generic/custom domain: use app entities, and adopt schemas if available for that domain.
• If your content matches a system domain: conforming to that schema is the intended path.
• For on-screen awareness: entities are required, and schemas make them more understandable.

If you want, I can also break down when to use App Entities vs App Intents vs App Schemas vs on-screen awareness in a simple decision table.