So I've gleaned this about Makima or the 'Control' Devil. Basically, it seems like she can completely subsume people's will. Especially people who die and she seems to naturally attract 'loyalty'. In fact, its clear Power knows exactly who Makima is from the beginning and is terrified to defy her (Either through fear of being subsumed or just how powerful Makima herself is). The same thing with Denji himself to an extent. The enjoyment and destruction of personalities and breaking people's wills down.
In all honesty, it should be a dead giveaway that Makima is something way more than she seems right from the beginning, because Power isn't afraid of any human, no matter how powerful (Aki or later on his trainer), but is absolutely PETRIFIED by Makima and there's really no reason she should be, as Makima is presented pretty much as a high level pencil pusher at that point. On that note, its fucking BATSHIT CRAZY that a manga called fucking 'Chainsaw Man' has better and more subtle foreshadowing than 2022 Hollywood.
Also, Chainsaw Man has to literally eat them to destroy concepts. Not merely kill them. And technically Chainsaw doesn't eat Makima, Denji does, which is why control wasn't eradicated. If it even could be, as its implied Control can understand, if only briefly, what concepts have been deleted.
I don't think she can control the dead, but basically anyone less powerful than her can be subsumed by her it seems as they're basically puppets of her will at that point. We can surmise that Chainsaw is stronger than her bonds of control, maybe because she never really saw Denji or even understood him. Its hard to say, as there's still a lot to go as the manga is still going on.
But I do look forward to the absolute implosion of the fanbase once its pretty clear anyone and everyone can die. Because if people are reeing about Kobeni and Makima being a groomer fucking lol at the future.