Yes, I second the concept of Calendar sharing. I can easily set up a shared calendar and invite family members, friends, or caretakers to the calendar, use Siri in iOS to add and edit the calendar event, and even share the event with other people if I so choose. That's a lot easier than having to download and install a new app, sync it up with all my currently existing calendars, and get everyone else to download and install the same app...

You can share your calendar with other people. You can even have a specific calendar for medical appointments that you share with your family.

Your app still doesn't do anything new and I don't want extra apps on my phone.

There's also no reason to reinvent the wheel and develop new voice assistants. Unless you think you can do it better than Google, Amazon and Apple. In which case, stop reading this and go make a billion bucks.