This looks like a good idea because BTC needs something like a DEX. I wonder how you can make it even more DEX. Would be great to link BTC addresses to email addresses. The users can validate there email addresses and that's all. Email confirmations can be sent out when funds are received in BTC addresses. Maybe buyers can cover the fees of the seller or split the fee when they  find and close a deal. For example there's a list of sell offers from verified email addresses attached to paired BTC addresses. Users don't have to sign up only pair email address to Bitcoin address or SOL or whatever is accepted.

Example, BTC for SOL trade agreement. All prices can be linked to the Coinbase API so it's real time. You could split the private keys up to the BTC and SOL address both users get the hash of each other's split of private keys. Create new address to both pairs BTC/SOL and you get half of the private key and the hash of the other half of key. So you send Bitcoin to the address and it's held there untill other user sends SOL to your sol address. Buyer sends SOL to seller address and the key splits are matched and automatically send seller BTC funds to buyers BTC address.  Then reveals other half of SOL keys to seller. Maybe you have to do the split with holding addresses for seller and buyer covers first fee buyer had to pay to send to holding address. I guess it's a split key system I think hal Finney talked about it. I dont know the technical coding language but you maybe able to make that work.