It's literally Lightning. I have built apps with the Breez SDK and sent sats to my wallet from my node.

But it is not free though. Their fee structure is quite a thing. You just pay as a % of your transfer. Plus privacy is pretty much gone.

You do pay a few sats but it's not like you're breaking the bank paying 3 sats on a zap. How is it not private?

No it's not. #Spark is confiscateable and has no unilateral exit.