Circle is the company managing USDC and is the one to watch for a similar number. They just IPO'd and will probably have more precise data in the next earnings report, but for IPO it seems they reported 2024 $1.5B revenue mostly from interest. I couldn't find holding percentages but as a founder of the token, we can assume much lies on Coinbase - they give a pretty good yield so any coins there will have fairly low interest income for Circle, and their revenue would be mostly coins moved off of Coinbase.

USDC is primarily holding a mix of treasuries and cash. It's unclear how much directly, but if you did some reverse engineering of the math, you could probably get a close idea. Since it's not regulated, the price can drop precipitously quicker than the stock market, so there's some risk calculation that determines their treasuries/cash split.