[HideousKojima]

> I know it has a builtin that does the same as Option<T> with its nullable types, like int?, which can either be an int or null

int? in C# is syntactic sugar for the type Nullable<int>. The big issue though is that Nullable<T> only works for value types, not reference types like string (or any classes). C# added "nullable reference types" a few versions ago, but that is just static analyzers in the compiler and IDEs, it doesn't actually enforce anything at runtime. And all of the methods, etc. that are available for value types with Nullable<T> don't work with nullable reference types.

C# has union types as a planned feature, which will also add an Option<T> type that will make it possible to handle nullability for both value and reference types using the same type, and make it so it's actually enforced at runtime.