feature request: abs-fontsize available for all text grobs

[Kieren MacMillan]

Hello,

There are a lot of places where I would like to use abs-fontsize: 
InstrumentName, LyricText, etc.

It would be nice if there were a built-in, intuitive, consistent, direct method 
of setting an absolute font size, e.g.,
    \override InstrumentName.font-size = #(abs-fontsize . 10)

How difficult would this be to implement?
(I'm happy to contribute a few euros in sponsorship funds.)

Thanks,
Kieren.