Yes thank you, you understand perfectly and thank you for explaining. Also, I LOVE your series of blog posts, thank you for making them!
Just to add to the general discussion for everyone following along - rollback netcode only sends inputs around, not state, so it doesn't really have much to send. I think I'm doing about 1.5 KB per second. When you point your mouse it sends that data in 10 bytes. There's not a lot to delta compress.
One cool trick you could try (although you are probably doing it already) is to include all inputs for some long period (like 1-2 seconds!) in every input packet the client sends to the server.
This way if one input packet gets lost, the very next one getting through will have all the inputs for the last 1-2 seconds, and this greatly improves how well your game will play under packet loss.
When you do this, you can even do an encoding from left -> right for all inputs, and actually, sort of delta encode inputs within the packet! Inputs don't change that much, so you can even get smart with the encoding and optimize it down to basically nothing.