I'm well aware of the Lambda psyop, really its ephemeral servers with some form persistent storage/db and a reverse proxy to a container control plane. Fancy talk for docker on the fly basically.

How are customers getting the invoice from the users node? CLINK could disintermediate this, all it would add is a nostr secret to the users key ring.

Sure but those users would use a custodial processor and you wouldn't need to tout it as have it be this innovative thing to make it "self-custody".

If your users aren't supposed to care, then why the extra steps?

It's not unreasonable to ask if you call something self-custody how did you solve it? I can't lab every library that makes fantastic claims, so looking for some signal first. If I was convinced, mdk might be a useful bootstrapping back-end in my stuff... but you seem resistant to any level of scrutiny.