Your phone (primary device) and the linked ones have to share the IK since that is the "root of trust" for you account: with that you generate new device keys, renew them and so on.
Those keys are backed by Keystore on Android, and some similar system on Windows/Linux, i'd assume the same for MacOS/iOS (but I don't know the details) so it's not as simple as just having access to your laptop, they'd need at least root.
Phishing is always tricky, probably impossible to counter sadly - each one of us would be susceptible at the wrong moment.
Those keys are backed by Keystore on Android, and some similar system on Windows/Linux, i'd assume the same for MacOS/iOS (but I don't know the details) so it's not as simple as just having access to your laptop, they'd need at least root.
Phishing is always tricky, probably impossible to counter sadly - each one of us would be susceptible at the wrong moment.