about the LN fees: it's a bit more than a nice starter I think! it would make the system an order of magnitude more useful imo (no fee fingerprint on chain) but I'm curious what you have in mind for how it could work. The way I saw it you essentially would need something equivalent to a submarine swap but with privacy, which means adaptors, which means PTLC and taproot and Schnorr (I'm thinking: payment secret is revealed by publishing signature for coinjoin). Even if that line of thinking is coherent, it's not only complex to implement, but relies on things that don't exist. Perhaps it could be done with ECDSA adaptors, which do exist, but .. well I hope it's already obvious why I always saw it as kind of "out there". Do you have something simpler (or just, better) in mind?