Display 2 decimal places in overview UI for a sensor

Does hiding the original entity prevent me from reading it?

No, hiding only hides it from the UI.

So, if it remains unavailable, the problem is that the 10.5 value mentioned is also not a number? Is the unit embedded in the state for the original sensor or something like that? Or is the value becoming available after a couple of minutes?

Please try dividing by 37.0