This article points out that businesses (LLCs, etc.) can also buy I bonds. A way to invest beyond the $10,000 (or $15,000) annual limit for individuals. Unless I'm missing something (which is possible) that seems legitimate.
https://thefinancebuff.com/buy-i-bonds-business-sole-proprietor-llc.html
Another one:
"You may also buy more I bonds through businesses, trusts or estates. For example, a married couple with separate businesses may each purchase $10,000 per company, plus $10,000 each as individuals, totaling $40,000."
https://www.cnbc.com/2022/05/02/i-bonds-to-deliver-a-record-9point62percent-interest-for-the-next-six-months.html