I don't mind the gray on my head. Just don't want people thinking I did a crazy bad job trimming my 'stache. Just tried twirling it to a point today. Finally long enough for a proper handlebar! Looks fine twisted together. No more dye. Yeah!Sooner or later it will all be gray. I understand the gray patches and unevenness. In the 80s when I grew a full bushy dark beard every Labor to Memorial day, I had a circle of gray on the right side of my chin about the size of a half-dollar. Looked weird but I left it. I've been clean shaven since a second job in the 90s banned beards. Now retired, my beard would probably look like my #1 buzz cut - 1/3 dark hairs, 2/3 silver. The silver areas look like bald patches on my head, but I don't care. I never wanted to look like everyone else anyway.
Oh, sorry, thought you were posting in reply to me without quoting. Makes perfect sense in response to OP. That would be something else! The filling in is for his “patches of no-growth areas on [his] cheeks...”
Alternatively Chia pet application might help in a pinch