2 is already happening. Facebook is pushing hard to get full data from partners to optimize ad tracking. Just look at the maximum data option for the Shopify integration now:
"The Maximum setting shares your customer's personal information to match users on Facebook's network. The information collected using this setting includes your customer's name, location, email address, and phone number, as well as their browsing behavior in your online store."
"The Maximum setting shares your customer's personal information to match users on Facebook's network. The information collected using this setting includes your customer's name, location, email address, and phone number, as well as their browsing behavior in your online store."
https://help.shopify.com/en/manual/promoting-marketing/analy...