Has anyone used with S2Membership?

If s2 membership uses WordPress’s default roles those roles will show up automatically in the menu item’s settings. If it does not and does it’s own custom thing for determining which users can do what you’d need to build some kind of bridge plugin.

For some ideas, you can take a look at these existing bridge plugins:
https://github.com/helgatheviking/nav-menu-roles-woocommerce-memberships
https://github.com/helgatheviking/nav-menu-roles-wishlists-memberships

Specifically you’d need to rewrite the helper functions section:
https://github.com/helgatheviking/nav-menu-roles-woocommerce-memberships/blob/master/nav-menu-roles-woocommerce-memberships.php#L93-L140

with the s2 versions for getting all the s2 roles, fetching the s2 roles (line 99) out of an array of the menu item’s chosen roles (matching line 120 to 106), and then using s2 functionality to determine if the current user has that assigned role (line 139).

Thank you for your very helpful reply.