No, you cannot.

var foo: (T | None) | None = None

Which None do you mean here?

This is just basic logic: (X or Y) or Y <=> X or Y

Untagged unions cannot model that. Contrast it with tagged unions:

var foo: Option<Option<T>> = Some(None)

var bar: Option<Option<T>> = None

Now you can reason about where the None means.