I've bought some different colours of wood filler to try again on the other side of the offcut.
I was going suggest that, but this can also send you down a rabbit hole and I didn't want to be responsible for that excursion .

Whilst it's great to have various colours on hand, it can add up financially when chasing the perfect match on a single current project.
Don't ask me how I know this...

You'll have to try and make sure to examine the cross-section of the end of toothpick and align anything that could be taken as grain with the grain of the headstock
Hopefully Simon is taking the Mickey here, but I've been down that rabbit hole as well and it didn't stop my self-diagnosed OCD from noticing the end grain of the toothpick in the earlier photo. It looked like it might be a bamboo toothpick rather than a hardwood one.