One interesting workflow I've seen is that the project maintainer simply rewrites and implements the pull request themselves and closes the PR.

LuaJIT has operated this way since 2012, though with a thanks and mention in the commit message. It seems like a good way to filter out people who prioritizes leveling up their github profiles.

Something a little bit similar, when I was hosting a social game server we had mods. And players always beg for mod status. At first I tried naming the admin group something weird like sandals, but eventually people would ask if they could be sandals too.

What worked best in the end was just hiding it completely making regular players see mods as other regular players. (mods would see who is a mod though)

I would also personally never make someone who asks a mod as it's almost always a sign of wanting power for the sake if it. I would instead just passively observe behavior until I trusted the player and make them a mod. I would then tell them that I don't expect them to exercise their power, but would demote if I see abuse of power.