Is due pronoun

No, the Word 'due' is an adjective, an adverb, and a noun.

Examples:

You must use due caution when driving in these conditions. (adjective)

We traveled due north until we saw it. (adverb)

He won the award, he finally got his due. (noun)

A pronoun is a Word that takes the place of a noun in a sentence. The pronoun that takes the place of the noun 'due' is it.

Example: He finally got his due. It was a long time coming. (the pronoun 'it' takes the place of the noun 'due' in the second sentence)