Yeah, no. This about the ePrivacy directive, if you don't have proper consent, you can't read/write tracers regardless of wether this is personnal data or not, except for tracers needed to establish the communication or demanded by the user (carts, login, etc).

EDIT: Thought about it, and if you only record the button click and does not identify the user, it works, and I am wrong! In general ePrivacy is very restrictive, only about access to terminal and not about personnal data ( and btw PII is not a GDPR thing, we say personnal data), but here it's ok! So yeah, no to me!