Smartphones are a very high target for everyone, from the FBI on down, and their attack surface is very large. So there is always (and will likely always be) se

Smartphones are a very high target for everyone, from the FBI on down, and their attack surface is very large. So there is always (and will likely always be) security vulnerabilities in any smartphone, regardless of the brand/vendor/etc. These can be gotten at remotely because these devices have WiFI, bluetooth, etc in them, making them much more accessible remotely. Yubikey's and the like are a high target item, but probably only for government-level adversaries, in general you have to be pretty well funded to attack these things, plus their attack surface is very very small, and most all of the attack surface is physical (i.e. you have to physically get the yubikey device to attempt any hacks on it). These devices generally only have a USB port, so to get at them remotely you have to first get remote access to the device(computer) they are plugged into, making it even harder of a target. That's the general overview. Specifically, SMS received tokens are not secure (because of the SMS part not being secure). NIST recently declared SMS based 2FA to be a bad idea, for instance.