Javascript in item definition label

Should it be possible to use a javascript in the label of an item definition?
I am trying something like:

Number Node7_Power "Consumption [JS(milli.js):%.3f kW]"

The actual value returned is in Watts, but I like to show (not convert) it as kilowatts.
If I use the above, basic UI show “NaN” as the value.

That would force a requirement for all possible UI to support javascript?

map and scale transform are supported. Those are handled server side?

This looks relevant

Relevant in the sense that this isn’t a working solution either. :sob: