The Cashu protocol and mint need to support Monero first. Keychat has a built-in Cashu wallet as a pocket wallet, not an on-chain wallet.
Discussion
How can we make that happen. Someone is working on ecash for Monero but I don't know if it is aligned?
nostr:npub1d7exvqfvxqyrq0j54e23gz6xj4lfj7qfssqamg60fkfp5f6mlzaskklrf3 is working on Monero ecash still I think, but not sure what the status is on that