Memory consumption of a pointer to vector of pointers

Question

I am aware that the size of a pointer is fixed (not the size of the data it points to). Now given that, supposing I have a vector of data in global scope and I declare a pointer

Answer 1

my_data will occupy sizeof(std::vector*) bytes, and no more than sizeof(void*).

*my_data will occupy sizeof(std::vector), which can be as little as 3 * sizeof(data**), i.e. no more than 3 * sizeof(void*).

*my_data will manage sizeof(data*) * my_data->capacity() bytes of dynamic memory.

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I have grave doubts that that information will be useful in practice.