What do you think about the approach 0xChat is taking with nip44 + gift wrapping + nip101 (alias keys). Seems like it takes privacy to a much higher degree.
I think it's good, but doesn't fix relay surveillance entirely (if you're AUTH'd and request stuff from an alias key then the relay can correlate the two keys). It also means other DM clients won't interoperate with 0xchat if they don't support alias keys.