As far as I know, it can only create a pointer of type A that actually points to a value of type B, not reference unallocated/deallocated memory. Nullable<T> could do that too if the language allowed it.

It's definitely possible to access unallocated memory e.g.,

// p points to address 1000

p := (*int)(unsafe.Pointer(uintptr(1000)))

Of course, this is why use of the unsafe package is heavily discouraged.