Earlier quoted context omitted.
How is that difficult? Anything that is stored to recognise a user on two different devices/sites is fingerprinting.
Oh no my session cookie! Remember Me On This Device: Not today Satan! Use code LINUS for immediate jail-time. Find My iPhone — You mean find my digital privacy regulator. I think the only way you're gonna swing it legally is by intention.
If you knowingly opt into being identified (like ticking an unticked "remember me" box that clearly explains the precise purpose of the identification) then it is okay.
If some asshat decides to do it without your informed, clear, and uncompelled consent, throw the fucker in the slammer.
It's not that complicated.