A long time ago I created m2mMesh, which was an Arduino library for a self-organising mesh network onESP8266/32 that allowed you to do machine-to-machine messaging.
This has been quite useful but sometimes it's overly heavyweight so I've written a simpler thing for direct links between two devices. Also with just two devices you can use the built in encryption features of ESP-NOW. Lack of encryption was always a concern with m2mMesh.
This new library is m2mDirect, which I intend to use for control/telemetry of the various rovers I've been working on.
It's not in the Arduino Library Manager yet as it needs more work, in particular ESP8266 support and channel negotiation, but it is now available on GitHub.