Ask HN: How do companies actually make money with fractional reserve banking?

I hear a lot of people talking about how Robinhood and Venmo make money on the cash that's sitting around in their accounts. I know they make money in other ways, but several articles point to this being a large portion of their profit.

I'm curious if anyone is aware of numbers of how much it's worth to a platform to have this type of cash sitting around.

For example, if I have $10,000 in balances sitting on accounts (assuming they are not withdrawing any of it), how much are you able to make per month/year? It seems that treasury bonds yield low single digit percentages per year. Is this the maximum I am able to make? Or are there other ways to leverage these assets?