BCH is trying to keep 0-conf alive by eliminating the artificial block space constraint, removing RBF (which is really dangerous when you have an RBF-flagged grandparent tx that maybe your wallet is t looking for), and implementing double spend proofs to warn tx recipients as soon as a double spend tx appears on the network. It’s obviously impossible for an unconfirmed Bitcoin tx to be guaranteed secure, but the risk can be minimized, which is nice for everyday, low value transactions.