If the feds have you device, they have everything, regardless of how hard you try to lock it down. Not worth even considering how to keep them out because you're simply not going to.
Also consider that, a sufficiently motivated private threat actor is likely going to break a pin, there's not enough entropy there, or they'll hit you with a $10 harbor freight pipe wrench until you tell them the pin.
For everything else, bitlocker, LUKS, or equivalent is more than sufficient and battle tested for those uses. Yes there are ways of breaking both, conditional on XYZ, etc, but, they're good enough. It does force you to multiboot, but that's good practice anyway, no reason someone using your computer should be using your root partition in 2024.
Let's not turn mountains into molehills here, Twitter isn't really closed, it's just authwalled. So, burner email is all you need to read all the tweets, errr, X's?, that you want.
Also, far simpler to take care of beeper, just make all the message bubbles the same color. They'd lose their entire userbase if that happened.
So "monopoly" as a single entity controlling a single market is a simplistic view of the issue at hand. Anti-trust is far broader than that, where any anticompetitive action can be subject to anti-trust lawsuits/regulatory action.
So the legal argument would be that, because Apple allows for a single messaging app, and interacting with that app requires an iphone, they're effectively preventing messaging app competition.
Apple has a very, very talented legal team though, so, for this to even see argument in court someone's going to have to realllly have to want it, and be able to fund it.
The thing is, users do care, they just don't understand how to articulate it. The Doherty threshold is real, and it's baked into our physiology as humans.
So it does bother them, it's not 'meh', it's just the status quo. Every once in awhile you run across an application or website that's fast, and it's jarring how much better it feels to use. That's something worth striving for.
The reason is that the money people don't want to pay for it. We absolutely have the coding talent to make efficient, maintainable code, what we don't have are the available payroll hours.
10x every project timeline and it's fixed, simple as.
Granted, the big downside is, you have to keep your talent motivated and on-task 10x as long, that's like turning a quarter horse into a plough horse, it's not likely to happen quickly, if at all. You'd really need to start over with the kids who are in highschool now writing calculator apps in python by making them re-write them in C and grade them on how few lines they use.
ie, it's a pipe dream, and will continue to be until we run out of hardware capability, which has been "soon" for the last 30 years, so don't hold your breath.