I would be interested in working on this with you. I'm in college for CS, and I have what I'm pretty sure is enough backend experience (and some frontend) to pull this off with you. I've never dealt with financial services before, but I've looked into payment processing a little bit and it doesn't seem too complicated.
Anyway, if you'd like, DM me and maybe we can find a time to chat.
How about a private channel in the EA Anywhere slack workspace (https://join.slack.com/t/eavirtualmeetupgroup/shared_invite/zt-1vi3r6c9d-gwT_7dQwMGoo~7cU1JH0XQ)? We can also mention the project in their software engineering channel and see if anyone else wants to work with us.
If this sounds good, join the workspace and then DM me (Aaron Fink) and I'll add you to a channel.