FTFY. (IOU=centralized token on the Waves blockchain)

There are no blockchain-based exchanges (Atomic swaps or blockchain-internal-token-exchanges) which can support real fiat money without intermediaries. The best try is actually Bisq.

I have outlined how a complete replacement for centralized exchanges could look like: https://bitcointalk.org/index.php?topic=4102739.msg38097740#msg38097740. It would be a mix of a Bisq-like protocol, stablecoins (like Dai or BitUSD) and atomic swaps (BarterDEX-like TierNolan-protocol-based or Lightning-based). The only thing it wouldn't support is high frequency trading.