I don't think so. Delta Chat seems a system running 'Chat over ICMP', so CoI goes on protocol layer, while Delta Chat goes on application layer.

Where do you see that Delta Chat uses ICMP ?

LOL. My bad. Its Chat over IMAP.

It sounds like CoI took (tempted to say hijacked) a subset of Delta Chat (protocol subset), something that was already shipping and working, and merely rebranded it.

Delta Chat is just a CoI client, as CoI webpage says.

"Thanks to Delta Chat Core, as a client developer you do not even need to deal with IMAP directly." https://www.coi-dev.org/