Hmm after re-reading this it is actually a somewhat genius idea. Use encrypted ephemeral events to ask a lightning node to pay an invoice. You could create a CLN plugin that connects to the damus relay, listening for encrypted ephemeral events from your key. This could be separate from your main key.

Then your nostr client only needs to send these encrypted requests to the relay. This also gets around firewall and NAT hole punching issues, since you are using the relay as a way to proxy the connection.

wow!