It's only technically impossible if the system software and/or hardware can't be compromised/exploited.

If you are just going by the intent and marketing of any platform vendor, plenty of things are technically impossible. But exploits and flaws in software and hardware exist, and the resources a nation state can bring to bear to find and use them are significant.

There is a reason vendors run bug bounty programmes, why the jailbreak scene is still a thing, and cybercrime in general is booming.

No one vendor has solved computer security.