Will Siri work with third-party apps in IOS 27?

Probably, but it can’t be confirmed yet for iOS 27.

Today, Siri already works with many third-party apps through App Intents and some SiriKit integrations, and Apple has been expanding Siri’s ability to act inside apps. So it’s reasonable to expect that third-party app support will continue in future iOS versions.

That said, iOS 27 has not been announced, and its exact features, supported app types, and developer APIs are not knowable yet. The details could change a lot by then.

Best answer: yes, likely in some form, but the exact level of third-party app support in iOS 27 will need official verification when Apple announces it.