I recently came across this while going through someone else's code
var name = Product.Buyer?.FirstName + " " + Product.Buyer?.LastName;
?. is called Null-conditional Operators, which is introduced in
Used to test for null before performing a member access (?.) or index (?[) operation. These operators help you write less code to handle null checks, especially for descending into data structures.
see the documentation and an example here