Based on my research the data available through the Linked API is very limited [1]. Basically `r_liteprofile` (name and photo), `r_emailaddress` (email) and `w_member_social` (post on a user's behalf). You can't get the users "vanity" url, profile information or posts. I'd love to be proven wrong though!
1. https://docs.microsoft.com/en-us/linkedin/shared/authenticat...