Ah nice didn't realize there was an integrated cashu wallet.
Is there any sort of arbitration or once you pay you're trusting the seller?
One way I can think to do this with cashu is P2PK locked tokens. 2/3 seller, buyer and a mediator. If there is no dispute seller and buyer can sign without a 3rd party. If there is a dispute mediator sides with seller or buyer.
fyi could be of interest: https://github.com/cashubtc/nuts/pull/124