XMR-BCH atomic swaps are possible, and work on a DEX is in progress.

The technique is based on XMR-BTC swap (Hoenisch, P. & Pino, L.: Atomic Swaps between Bitcoin and Monero (2021), but instead of relying on SegWit/multisig to enforce TX template we directly use covenants, which became available on BCH with '18 & '22 network upgrades.

The DEX is being worked on and here's the latest update from /u/mainnet_pat:

$BCH ???? $XMR atomic swap update. Finished the core functionality of the swap and implemented the happy path and refund path in a big integration test suite as per contract v4 by bchautist. One last push to support to v4.1 and I can start working on the Web3 dApp!

Check out the great SwapLock contract research and optimization at BCR

Big thanks to Woodser for helping me out with great monero-ts library and all other Monero people for being friendly and responsive

Cross-chain Atomic Swaps With Bitcoin Cash (BCH) Using One-Time Verifiably Encrypted Signatures (VES)

Abstract. With advances in cryptography, it became possible to implement atomic swaps between Bitcoin (BTC) and Monero (XMR) and two such protocols have been successfuly demonstrated. However, the protocols require the scriptable network to have 2nd-party malleability solved and list SegWit as a requirement. With advances in Bitcoin Cash (BCH) smart contract capabilities, it became possible to implement an equivalent atomic swap protocol despite BCH network not having SegWit.

In this work, we present our solution to cross-chain atomic swaps between Bitcoin Cash (BCH) and Monero (XMR), using adaptor signatures and discrete logarithm equivalence proofs. Our solution uses newly available native introspection opcodes to commit to transactions contents, making it immune to 2nd-party malleability, and with transaction size significantly reduced compared to previous work. We also introduce a cross-chain atomic swap between Bitcoin Cash (BCH) and Bitcoin (BTC), using similar approach.

Keywords: Blockchain · Atomic Swap · Bitcoin Cash · Monero · Adaptor Signatures.