Well, I guess it depends on how you want to go about it. It occurs to me there are 3 different repairs here.
The mahogany I would be inclined to repair with epoxy putty. If you are going to grain fill the area, which I recommend, you could cut fake grain lines into the putty and adjust the area afterwards with an airbrush. As it is inside the slot, it is going to be super hard to get to a bunch of angles of observation that will make the lack of chatoyance apparent.
The pale laminate and the (assuming) ebony peghead overlay, I would use wood and do something similar to the scoopie technique from the Ding Kings episodes on the subject. Do you have any cutoff left over from roughing out the shape of the peghead ? If so, I would glue a slice of that on and trim it back by hand after the glue dries.
perhaps a bit of filing, long strokes the full length of the slot, blending that into the remaining slot. The thing is it seems like it’s only in your inner layer so it’s probably not going to be all that visible to anyone. It’s also a “non-player side” error, the person playing the guitar is not going to see it.
Definitely an easy one to make the repair look worse than the error.
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