SN is still a custodian of sats with a concentration of operational burden.

While SN doesn't really need the privacy of eCash (you can do accounts in a Fedimint too, btw), the distributed keys of a Fedimint might be more advantageous than current setup (of which I am completely ignorant). You distribute load between the guardian servers and distribute risk by having keys disagregated. This could also allow for stackers to run LN gateways for SN, reducing operational requirements and creating redundancy.

Privacy is cool, but reliability, redundancy, and security improvements are also very cool. Would be happy to shill... errr... chat more about Fedimint any time.