[Seeking] Plugin to enable instant delivery of products

I’ve been looking around, but have been unable to find something that matches what I’m after.

I have an ecommerce store, and I’m looking to enable some sort of instant delivery for customers who are new and want to “test” out our site.

The scenario:
I have a list of unique account information that people will buy. It’s not a subscription, but account info (user/pass) that I want to have delivered to the customers email upon checking out.

I’m looking to be able to load the user/pass info in, and have it send one out when somebody orders something.

That way they don’t have to wait for me to fill the order, it gets sent out instantly and they can see we indeed provide what we say we do.

I’m not sure if that makes sense or not. But does anybody know of any sort of plugin that can accomplish this?
I can be free or paid, I assume something like this would be a paid plugin.

Thank you!