OCAPI supports correlating data across devices for guests and logged in customers, which applies to both client and server side activities.
How:
Client side activities use the visit_id as an
identifier for guest users. After the user logs in, use a combination of hashed_login + visit_id.
Server side activities Use the visit_id as an
identifier for guest users. After the user logs in, use a combination of hashed_login + visit_id.