It's currently only listed at MEXC yes. Due to the nature of exchange listings, teams have to sign NDA's that don't allow them to discuss these listings prior to them happening. We simply won't know until they go live. Uphold (and some of their staff) have mentioned Koin quite a bit on twitter so that one in particular seems likely. It's only 3 months old, so it'll probably be awhile before you see things like Binance listings (in my opinion - could be wrong). KoinDX is like uniswap so any tokens that are on Koinos could be traded there as any pair. The software for a bridge is being tested on the testnet at the moment so we can assume once that goes live we'll start to see wrapped tokens from ETH on Koinos and also wrapped Koin on ETH. This also would give more trading pairs that could be available on KoinDX.