Hey my friend!
Even though I think it is very nice & generous that you are offering this new service for free at the moment, I do think you need to consider charging a very small fee to compensate for your time especially if you plan on offering this service long term and in case you get lots of customers (just don’t want you getting overwhelmed without anything to compensate/show for it)!
Just want to look out for you my friend especially since you are offering something unique!
As long as you offer amazing customer service and are prompt, I believe that you will do really well and I don’t think people would mind paying you a small amount for your services!