If a user is not signed in, there is no reliable way to identify which user the data belongs to.
You can go down a rabbit hole of scraping together various pieces of device info to identify a user’s device, but this is challenge for even the largest advertising companies that try to track ad views. The thing is, browsers make there best effort to protect your privacy, so it’s very hard from the developer side to reliably track a specific user or link data to that user if they have not identified themselves.
Short of having a user to identify themselves somehow to pull settings unique to that user, there isn’t really a good way to link data to a non signed in user.