Just out of curiosity, I think it would be interesting to build a transaction bridge between Lightning and Monero.

Maybe something like: you enter the Monero address you want to pay with your Lightning wallet, it generates a Lightning invoice, and once settled, seamlessly converts those sats to Monero and sends them to the recipient's wallet, vice-versa

Not sure if there’s a real-world use case for it, but it could be an interesting experiment.