I think the relevant comparison is the developer beta, which has access to the Gemini-powered Siri that will roll out publicly later this year. From the reviews I've seen, Apple won't be "years behind" (which surely they were) for long.
I am on the developer beta for iOS/iPadOS/macOS and all I see is still just the OpenAI option.
That said, Siri seems a little bit better now - my subjective opinion. It is a little bit less frustrating.
But not in the EU, because of the DMA :/
I did say iOS 27. I am using the new Siri. It’s better, but extremely unreliable (half of all requests fail) and slow. It should be like a Codex running on my phone with the ability to chain skills (intents) to execute a task, but it’s too crappy for that.
And the voice is still a poor text to speech model, very far behind GPT live.