I’m certainly open to discussing all possibilities with you, and I have accepted code contributions to the main (free) plugin from other developers in the past. I see this as being more of an add-on extension, though, as opposed to something hard-coded into the main plugin. The main plugin has a LOT of action/filter hooks included already to make it very easy to extend.
I would suggest contacting me privately when you are ready, and we can discuss via regular email or phone. Use the contact form, or just put stephen in front of my domain name for my email address.