You are talking about an exchange with all the features of Binance except that it shouldn't have a CZ on top of it.

Cross chain transfers are something that are seen as a holy grail. Cosmos and several other claim to have been built from the bottoms-up with an approach to have the ability to "talk" to any blockchain. This means that the protocol is there but specific applications needs to be built which need developers' time and funding for them. This has led to a scenario in alt-coins where funding is made available through sponsors and hackathons to open source developers around the world. They hope to achieve a network effect of enough chains and enough projects.

IMO, they all suffer from the same basic flaw. In the name of transaction speed and inter-operability, they compromise with the basic value proposition of blockchain to act as money. They use various forms of PoS instead of PoW. Expecting Bitcoin millionaires to trust their money freely to a set of "validators" is a little too much to ask. This doesn't mean that people aren't doing it. Lot of Bitcoin moves cross chain through wrapping services. People already use these partly decentralized services for wrapping tokens for use on other chains.

If you are going to compromise with PoW at some level, then why not do it at product level rather than protocol itself? This is why such a proposed DEX can only be an academic curiosity and not really something that traders need or will risk their money with.