Like you can't install any software on iPhone that has not been "blessed" (aka signed) by one Apple's private keys. Well unless you find an exploit to free the device from their control. What is so crazy about this is Apple does not even own the hardware after they sell it, but they won't let you disable signing in the boot ROM or at the OS level. If it were about security they would at least let you load your own signing keys. It's not though in my opinion it's about control. I even consider it a violation of property rights.
This is simply because if you own something you should be able have full enjoyment of your property without interference. Further, one major fundamental aspect of owning tangible property is the right of exclusion. The cryptographic system Apple has setup allows Apple to control the right of exclusion when it comes to deciding what software the CPU will and will not run. Apple is effectively reserving the right of exclusion regarding what CPU can execute via cryptography. Crucially, when something is sold legally this means all property rights are transferred to the buyer with few exceptions. One being copyright the original holder of the intangible property reserves/retains the right to copy/reproduce. Despite not legally having the right of exclusion Apple decides what can be excluded from running on other peoples hardware even after selling it.
The short and simple is I should be able to decide what to include or exclude from something I own. In this case, one must ask Apple first which shows how your right of exclusion has been infringed.
This also applies to other devices not just iDevices, but anything with locked down boot ROMs/loaders, but Apple is well known for their "walled garden" (I don't like this term nothing garden like about property right violations).
As for tik tok it's an easy target for such government overreach.