iPhone can be hacked. It’s just exceedingly expensive, based on available evidence. Remote no-click iOS exploits with persistence are currently worth up to two million dollars each, give or take.
Apple themselves provide related info about exploits, and Apple has provided notifications to some users when they suspect compromises: About Apple threat notifications and protecting against mercenary spyware - Apple Support
SIM swapping is a thing too yes, though there are options to eliminate the exposure to that, particularly involving security keys.
But since you clearly believe you have been hacked by folks seemingly with immense budgets and carrier access, or with immediate local direct access (whether gaslighting or otherwise), and have undoubtedly already taken the basic steps to re-secure your environment (and failed) (though oddly lacking security keys), that automatically puts you well outside the sort of help that can be offered around here, or in most any other forum.
You can continue with these requests in this and other forums of course, and you will get the same suggestions previously offered, already considered, and already failed.
You will need specialized forensics help, or you need to learn about forensics and collect some evidence yourself. If not what you learn and collect, you’ll either need to pay for forensics help, or you’ll need to differentiate your requests for (free) help with the immense numbers of other folks also seeking that same (limited) (free) help too, as they’re not inundated with requests.
Lots of folks think they were hacked. Most have not been. The “I’ve got a virus” and “I’ve been hacked” claims are often wrong. More than a few of these reports have been caused by benign and mundane software changes of software bugs, or by hardware failures. Not by security issues. And if you have been hacked, you’re outside the portfolio of anybody around here.
Or put more succinctly, you have reached the limits of your current approach, and will need to change your strategy.
