Is speaker an indirect object

Yes, the Word 'speaker' is a noun, a Word for a person.

A noun will function as the subject of a sentence or a clause, and as the object of a verb or a preposition.

For example, in the sentence, "Give the speaker your complete attention.", the noun speaker is the indirect objectof the verb 'give'. The direct object of the verb 'give' is attention.

Note: The subject of the sentence is implied (You give...).

Examples of other functions of the noun 'speaker' are:

The speaker today is Professor Zemljevidih. (subject of the sentence)

The notes that the speaker was reading fell to the floor. (subject of the relative clause)

We've booked the speaker for another lecture. (direct object of the verb 'booked')

The dean signed a contract with the speaker. (object of the preposition 'with')