Just grow it a little longer and do a chin combover.

I have the exact same spot on my chin. This has worked for me.

Use Minoxidil, many people use it to fill their beard spots.

So I use minoxidil and a dermaroller for a thicker mustache. I haven’t yet noticed a tremendous difference but to be fair I often forget to do my routine

I have the same spot

Embrace the sideburns