Yep, I did misunderstand. I thought you wanted to be able to allow your wife to access your personal information, but now understand that you want it to allow her personal information based on her voice recognition.
In any case, what you are wanting is not possible with the HomePod. Only your personal information is accessible using your voice recognition. It is a multiple user platform in the sense that anyone can direct it to play music or control your home accessories, but it is not able to access multiple users private information based on their voice. Your personal requests are detailed here on this support article:
Make Personal Requests on HomePod - Apple Support
If there is enough interest, it may be something they implement in the future and the feedback link may help.