My understanding is that a plane is designed with a particular powerplant in mind so such a partnership would be make or break.
https://www.reuters.com/business/aerospace-defense/boom-supe...
I don't really see how this will be a success commercially with the whole CO2 crisis going on, though I could imagine that some militaries will want a faster troop transport or something.
But I think with the increased scrutiny on carbon emissions this will not fly anymore (pun intended). See how celebs are being criticised for using their private jets for example. This will only get worse. Then using a plane that emits much more carbon for the same distance (even though it's much faster) will definitely make it harder to justify.
There are 2 sets of rules: The laws that tell me I can not get to work in my 23-year-old pickup truck, and those rules do not apply to people who can fly private jets. Those people fly private jumbo jets to environmental conferences.
I know this will be an unpopular opinion on HN, but what if we banned all civilian air travel (I mean ALL civilian air travel) until they can prove they meet the emissions standards and fuel economy standards my 23 year old pickup has to meet to pass emissions testing every year.
The only planes using leaded are general aviation light aircraft that still use AVGAS 100LL. Jets use only Jet A-1 which is unleaded kerosine (though technically they can burn almost anything which is one of the cool things of jets but of course for reliability and safety this is not done in aircraft). The M1 Abrams tank touts this as a major advantage though, if you're in a pinch you can pour pretty much anything that burns in the tank. Just a shitload of it :)