Add small clock to right margin of dashboard header (like on Android phone)

I would like to add a small digital clock to the right edge of ideally every dashboard header.
Goal is to have an unobtrusive clock that does not consume any of the valuable dashboard real estate – and instead just uses the generally blank right edge of the dashboard header.

Look would be similar to how the clock looks on an Android phone (e.g., 2:44 PM in the stock photo below)

Even better would be the ability to add other widgets/icons too!

Possible solutions for this were proposed here:

Currently it is only possible with card-mod theme, so suggest to use that thread