How do you start a US Bank?

Y Combinator posted a video on their youtube channel recently about Tom Blomfield's startup story. In it, he mentions they were able to create a prototype bank using prepaid debit cards in 3 to 4 months: https://youtu.be/QKPgBAnbc10?si=-4oBvHysWWU02Pm2&t=345 In the video, he made it sound simple. Like anyone can just go about and start a banking app. He was apart of a previously successful startup before Monzo. Did he get some exit money and this is how he was able to create a bank? Seems like that's what Elon Musk did with X before the merger with Paypal. Anyways, I have a startup idea that I'm pretty sure I would need to own my own bank to start. One of the features is the user should be able to quickly create as many debit accounts as they want in like less than three taps. Most of these debit accounts are just temporary though. The debit account needs to have a debit card attached which is a virtual card (you never get a physical one in the mail). Maybe a prepaid debit card fits this criteria. I don't know the difference between the two. In addition to these temporary debt accounts, you also have your primary debit account that can accept direct deposits. Do I need my own bank to do this? If I do, how would I go about starting one? I'm guessing from the jump I'll need capitol for the bank part. My thought was to build a landing page with a paid waitlist. After some traction apply to YC and go from there.