In the video, Torgersen says the nullability feature was inspired by TypeScript. Torgersen says he consulted TypeScript creator Anders Heijlsberg to build the nullable reference feature.

As a heavy TypeScript user myself, it was easy to see the parallels between the designs: question mark nullability, the compiler-enforced nullability checks rather than runtime-enforced, "dammit operator" to override the compiler. All shared between TypeScript and C#.

I love this feature in TypeScript; it's help me find numerous bugs and helps me reason about my code. I'm looking forward to using it in C#.