Not entirely what you are looking for, but maybe of interest. Taking the channel of the ZigZagZug ( ) indicator as Fib 0-100 range and not allowing Fib to switch direction (normally when trend is up 0 is low and 100 is high and when trend is down 0 is high and 100 is low, now the bottom of the channel is always 0 and the top is always 100).
So that allows for the creation of an oscillator and when you are in a down trend you need to 100 - OscFib value to get the fib value one is used to. The oscillator is subjected to jurik filtering to make it smooth.
And in the bottom window is the resulting oscillator:
It is still intriguing to me, so maybe it can be to others.