Endgame system here will not be Iron dome as it is now. Skyhunter would the son of Iron done, an Americanized system. They want to fork the technology.The Iron Dome uses source code that is highly classified and belongs to the IDF and Rafael. If the IDF does not give permission, Rafael cannot transfer it.
However, measures are being taken to make the source code more accessible to the US, and perhaps through Raytheon.
So, it's a matter of time.
The two systems would have common hardware but the OS and some of the package would change. Think of it like Android and IPhone. They have similar hardware but the Software the source codes are (likely to be) incompatible despite both OS being based off a common root.
Iron dome bought buy the US army is more or less stock Iron dome with the source code issues. However for a major army like the US you can’t expect them to deploy such a system probably in numbers that might dwarf the IDF without tailoring to their needs,
The US Army wants to plug its future Indirect Fire Protection Capability system into the same network as PAC and other assets. To get via the network a heads up of incoming threats before they are on the systems own Radar and have the same type of networked US communications not currently available to the US via iron dome.
This is why the shoot off. To see if Raytheon can deliver or if the competition could an Iron dome like system that is compatible with the rest of the air defense network.