Special products for special customers only

In the admin in the customer area we add a button: “Can see special products yes / no” and in the products we add: “is a special product yes / no”
The result: only customers with “Can see special product” can see and buy special products. 
Including consideration of product listings, search results, special offers, cross-selling etc pp.

This is very practical if you only want to make individual products accessible to wholesalers or other customer groups, but otherwise do not want to work with the customer group system in the store. 

This is not a system module, but an individual program.