Information overlay mod - Is something like this possible?

This design would not be possible as a mod and would need to be an external program that overlays to the game, using something like Electron. I recommend instead to make a basic immediate interaction that outputs the values as a regular notification, it would be relatively quick and easy and won't drive you crazy for a simple feature.
Lot51 is making an overlay companion for the game, and I believe he might have something planned where you can view stats of everyone in the household, but it's been a while so I'm not entirely sure. But it will come with other features, so if you don't want the extra features when it eventually releases then notification is the way.