Check if Current User is Connected to Current Post

I would like to restrict access to read a post based on whether or not the current user logged in is connected to the post they are attempting to view, or if they are connected to a CPT that is connected to the current post, sort of a distant relative connection.

Has anyone done either or know how to compare the current user to a connected user?

Thanks in advance.

https://www.ads-software.com/extend/plugins/posts-to-posts/