"what" and "who" are examples of blank pronouns

A pronoun is a word, which we use instead of a noun, usually to avoid boring repetitions. For example, in the following sentence, I am going to swap the word "pronouns" for the word "them", simply because you will get bored if I fill each sentence with the word "pronoun". There are various forms of them.

Subject pronouns: I, You, He, She, It, We, You, They

Object pronouns: Me, You, Him, Her, It, Us, You, Them

Possessive pronouns: Mine, Yours, His, Hers, Its, Ours, Yours, Theirs

Relative pronouns: Which, whose, that, where, whenetc...

I could go on, but I reckon you get the idea now. Ironically, the word "pronoun" is actually a noun.

So the answer yes