Something I learned yesterday planning a trip to France - you can purchase an at-home antigen test that can be proctored virtually and counts for US entry. Only available to US addresses and must be purchased before leaving the country. Download an app and take 15-30 minutes to do the virtual test and get certified results. The only issues is making sure you have some time on your last day of travel as well as a WIFI connection.
It's the same Abbot test as Binax-Now but it has to be specifically purchased for "at-home" rather than "self-testing." Here's a link.
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Delta, United, and American also partner with them, but seem to have higher prices per test (but the ability to buy fewer tests). Currently, tests expire in late winter or early spring, but I'm sure the authorizations will be extended (or the ability to buy new tests).
I agree 24 hours is a very tight turnaround, but it is possible. France appears to have 48 hours (from time of flight), so now it's a waiting game to see if this at-home version will work for the French as it does for the US.
For anyone originating outside of the US, check with your airlines - they will likely have testing information and links to where to get tested that satisfies the requirements.