Star Trek: Discovery's season 2 finale decisively resolved the Control storyline and appears to have wiped out the entity completely. The conclusion also stamped a bright red "Rejected" on the theory that posited Control would somehow be connected to the Borg.
The malevolent A.I. that sprang from Section 31's threat assessment software bore stylistic similarities to the Borg that became so obvious it seemed they had to be intentional. Control's desire to consume the universe like locusts combined with their disdain for humanity rang very familiar, and when they essentially assimilated a (bald) captain to serve as their mouthpiece and growled "Struggle is pointless," at his resistance, it seemed impossible that Control wouldn't somehow be connected to Star Trek's most iconic villains.
But part two of Star Trek: Discovery's season 2 finale, "Such Sweet Sorrow" seemed to indicate the details connecting Control to the Borg were only superficial. When Georgiou destroys Leland and Discovery disappears into the future and out of the history books, it certainly seems like the book is closed on Control with no possible way left for it to connect to the cybernetic beings in the Delta Quadrant. So that theory about them somehow getting sent back in time and somehow becoming the source of the worst guests in Star Trek? It's probably not true.
Leland's grey veins, control's predilection for red laser eye play, its use of nanotech to spread like a virus and eliminate individuality - none of that had anything canonically to do with the Borg. In fact, in an interview with TrekCore, co-showrunner Michelle Paradise insisted the writers never intended there to be any connection between Control or the Borg, canonically or stylistically: "It’s interesting — we weren’t thinking Borg at all. I mean, we talked about all sorts of different things in the room, but there was never any intent on our part to parallel that in any way. I can certainly understand why people started to think we were going in that direction, but it was never where we intended to go with it." Given Discovery's penchant for integrating previous elements of Star Trek into its storyline at what some would say is the expense of originality, the fact that Control was not be shoehorned into a Borg origin story no one asked for is undeniably a good thing.
Unfortunately, as hard as it is to believe Control could've found its way into Borg history, it's equally as hard to believe Discovery didn't intentionally evoke the species in their characterization of Leland and Control. The similarities are too glaring not to think that at some point there was an idea to connect the A.I. and the Borg that was later abandoned, or that the stylistic callbacks and variation-on-a-theme catchphrase weren't an attempt at mining yet more nostalgia from the greater franchise.
While actually going through with establishing Control as part of the Borg's backstory would've been frustrating, without that context, the similarities between the two entities make Control feel less original and less compelling. Ultimately, Georgiou's clever use of magnets was the best thing to happen to this story, hands down.