ESP-NOW Networking
This is a cleaver contribution by Espressif (CN) to allow very simple networks using their small processors.
Limited use of the OSI Model
This is shown below. Only the physical and link layers are utilized. As such it is "fire and forget", like UDP. No INQ/ACK, retransmission or reordering of packets.
You can use Seeed Studio's ESP32-C6 chip for each side of this network for an open-air range of over 800'!