Finished implementing protobufs as the serialization protocol to be used throughout the system, including over the serial port and in the log and configuration files on the NOR flash.
In the process of implementing protobufs, I realized that I also needed a framing format to "wrap" the protobufs in. I originally considered SLIP's framing, and then realized that the KISS protocol was an easier-to-parse superset of SLIP, with the bonus of being directly supported by many amateur radio applications.
As a result, my journey through protobufs has made QMesh a KISS-compatible TNC. This means that, using e.g. an HC-05 (HC-05 info/usage) UART-to-Bluetooth bridge, APRSDroid now works with QMesh. Codec2 Walkie Talkie (Github repo here) should also work with it, but I've been focusing on performance tweaks/enhancements to QMesh before giving it a try. Note that I also added in the ability to fragment KISS frames across multiple QMesh frames if the KISS frames are larger than a single QMesh frame.
After burning up an STM32 board and an HC-05 board trying to update an outdoor QMesh node, I've been working on developing a wireless, ESP32-based remote administration of the outdoor nodes. Basically, the ESP32 would connect to my Wi-Fi network, and allow me a network-based method to access the UART for testing and remotely updating the firmware (I'm also working on a bootloader to update the "main" firmware).