I'm not sure I understand. From a quick google search it seems like they are designing and manufacturing it themselves (with a few partners). Am I missing something, or is your information out of date?
The industrial bases of entire nations military aviation have been taxed for years/decades to produce supersonic capable engines simply for high maintenance fighters, now do that for affordable maintenance low headcount passenger jets. I'm not going to say impossible, but it will take more than VC money and anonymous 'partners' to convince me its likely.
For it to have a chance the US gov. needs to do IP transfer and pair them with NASA for test as they did with SpaceX, more realistically simply twist Pratt&Whitneys arm a bit...
They have not committed to an engine. There is no engine commercially available to buy and no engine producer has committed to creating one.