Linda Ann’s Answer
If the skills that you are developing in your volunteer gig are consistent with the skills a prospective employer is looking for, then the answer is YES.
It is important that the person(s) who is supervising you at the volunteer gig has sufficient opportunity to see you in action, so to speak. Why? So that this person can serve as a credible reference when you apply for work. They also must be willing to serve in the capacity of a reference; that means of course that you've had a conversation with this person(s) about their willingness to take on this responsibility.
It is very noble that you are volunteering. Bravo.