No, but there's a direct correlation. Once you play with it a bit, you can pick the percentage that gives you the dB you want.
That also means it shouldn't be too hard for
@Warmuptill to add a choice of units, right? (until someone wants to use a variable with both units in different places)
That said though, I've only ever used 0% and 100%, which makes this point mostly moot. My actual mix is done with the compressors' makeup gains, since they're already there anyway. I use a DAW for all that, but it works in OBS too.