> With nicer syntax, nulls are equivalent to Maybe types.

In a language that lacks maybes, but has nulls, what is the equivalent of the type Maybe (Maybe Int)?

> Recent C# for example has the ?. and ?? operators, which are flatMap and orElse.

Even ignoring the lack of composability, flatMap is an operation on a broad category of which Maybe is one example; that generality is a key part of its utility. ?. is a special-case operation on nullables, if you want to use it on any of the other things that flatMap works on (e.g., lists), you need a different operation, so you can't build generic algorithms. So, its not substantively the equivalent of what Maybe provides in languages where maybe is part of some broader category of operations on which flatMap can be applied.