The fact is that on true decentralized exchanges, you can decide to use the address that you generate on your own noncustodial wallet to receive the coins. You can generate seeds phrase, private key and the address on the exchange but yet you can decide receive the coins at any noncustodial wallet address of your choice.
For derivative trading, I do not think there can be a decentralized exchange for it. Those that called themselves decentralized like this one are not actually decentralized but centralized.
Yes, I know that DEXs allow you to put your address and work like this and to be honest, is the best and true crypto way. But for trading in constant mode/ day by day, they need volume, thus people. And most of them are focus on CEXs. It's very difficult to change their way of thinking and make them go on a DEX and start trading there. However, I believe that now that all the CEXs want more and more KYC, people will realize that the only way are DEXs.