So the idea would be that a Cashu (or any other Lightning wallet) would be sitting in the background listening for incoming DMs from the owner and treat them as commands for paying etc?
Interesting.
Discussion
Yep.. they are not DMs m, but you got the point. Basically an Umbrel plugin service could bekstening it for users. That plugin can then have multiple privacy + security protections such as the authorized amount per day, frequency of transactions, etc.
We should be able to extend it to your needs if it's the case.