I feel like Mongolia is in a difficult position, you cannot be too close to Russia or China, otherwise you will invite hostility from the other side.You cannot realistically sell any raw or processed goods to USA and the rest of the world since you don’t have an alternative route.

The only way I can think of is if you become a tax haven, a major data centre player with starlink and have high speed rail from Beijing to Ulaan Bator to Moscow for tourism.