In the article the author mentions that Duet doesn't seek any sort of credentials and mentions connecting repos, so I think that this assistant is being used more for managing coding work in a different way than managing life work. I do agree that to get to true "personal assistant" levels, like planning a whole trip for you, booking tickets, etc. you'd have to give pretty much full access to your identity and money, but people claiming it can do that probably are just handing it over, security issues aside.