This is just an opinion, but unless you have a large established brand as a payment provider Shopify is probably not going to be interested in offering it as an option. If you look at the currently available payment providers they are all major worldwide companies doing millions, or billions in transactions annually. As is Shopify, so they want to collaborate with other major brands and influencers. I do not work for Shopify, so like I said this is just my opinion.
It may be possible to integrate with Shopify in some way, but not sure on how that would be done. If you are serious about this idea, it would be best to contact Shopify directly with information about the services you offer and see what their response is. Good luck!