Why not? I cannot think of a musical reason why Dorico should not permit this. So how to do it? Engrave mode does not let me shift the pedal line all the way left needed.
I cannot make this work, despite an earlier post some time ago with good advice:
Using the properties panel grace note start/end options achieves no visible effect.
Pedal lines can’t actually attach at grace note positions. Dorico will automatically draw the start of a pedal line aligned with the start of a group of grace notes at the same primary position as the note where the pedal line begins, but it isn’t (currently, at least) able to do that for grace notes before the barline. So for the time being you have no choice but to adjust the start position of the pedal line in Engrave mode.