I'm aware of the programs Snowden revealed, Tempora / XKeyscore / Longhaul / the like, plus I've heard J. Edgar Hoover did bad things and lots of CIA meddling internationally was bad. Still, these seem qualitatively different to the explicit blackmail you're referring to.
Do you (or someone else reading this) know of historical examples that demonstrate a pattern of this sort of thing? You can interpret "this sort of thing" as you wish.
That's a lot to ask for on the spot, so if not, I would be interested in what generally makes you approach the situation from this cynical angle, especially given that it's the FBI. In my experience, which is fairly limited but is as a US citizen, most of the time the US government mostly follows the law and doesn't do this sort of thing to citizens.
It's so much easier just to "recruit" the direct manager of the firmware engineering team. Convince them it's their patriotic duty to add "tracking dots" to the design requirements without drawing attention to where the requirement came from.
The engineers implementing it will assume the requirement came from somewhere above, or another engineering team. And if the executives ever notice, they will assume it came from somewhere below. Both will probably assume the legal department was responsible, and that there is some kind of law somewhere requiring them to implement that functionality.
Moreover, most executives don't require blackmail; they tend to go along to get along.
If you want examples of events that could be reasonably interpreted as “this sort of thing”, the son of the guy who tried to assassinate Trump the second time was mysteriously arrested for possession of CSAM a week after his dad was arrested. I’m inclined to believe that the base rate of people being into that stuff is reasonably low so whenever I hear about someone being charged with it in relation to a completely unrelated major news story it gets my spidey sense tingling.
Big company executives are easiest to control; they want money and all of it. US Government luckily has plenty of it to throw around.