When you look at cost, the An-124 Ruslan would have been a good addition for the US in heavy transport. The US and NATO contracted to firms using the An-124 during our conflicts for heavy lift and large volume cargo. I saw one in person in Seattle back in 1998 or 1999 at SeaTac Airport parked and was impressed with it.
I found out Boeing used it for large parts transport during that time. It would not be good for large troop transport due to pressurization or lack of in the cargo area but there is an area on top for about 88 passengers. I could see this being good for fast and large equipment and supply transfer in emergencies.
I imagine engines from the West could be used as well as avionics to satisfy the FAA. If Boeing can be certified, I can’t see why anyone else can’t. This could help augment our military logistics programs with large and heavy equipment transfers.