Yes, GPT is particularly good understanding, even when you misspell things. It would make a good front-end interface to something like Siri. take the human input and make it something that makes sense to the dumb computer.
Yes, but large language models are very compute intensive and require a ton of RAM. So they wouldn't be able to run locally (this is currently possible with Siri), would be relatively expensive and possibly slow. So they might still be a while off.