Is little an indefinite pronoun

Yes, the Word 'little' is an indefinite pronoun when it takes the place of a noun for an unknown, small amount.

The Word 'little' is an adjective when it is placed before a noun to describe that noun.

Examples:

Little is known about the cause of the disease. (indefinite pronoun)

The little tree that we planted is now as tall as the house. (adjective)