GATT Connectivity in ESP BLE Mesh

[freeride01]

Hi,
I am currently getting acquainted with the BLE mesh protocol and I want to make sure I understand the key concepts right.
From what I've read so far it seems that the only communication through an actual connection (GATT server to GATT client) is established during provisioning between the provisioner (smartphone) and the proxy node in the BLE mesh network. All other communication is connection-less, via the advertising packet. Is that correct?
Are there any other cases when the protocol allows a node-to-node connection?
If not, is it possible to add such option through the API in ESP-IDF?
Thanks in advance.