I really like how this is progressing. Thank you for the work you have put into it.
My wish list, and maybe it would be a good idea to do a poll of some sort to see what other think, is as follows:
Rotary encoder for ‘canned messages’ see this thread Should not take much space and they seem cheep compared to the functions they allow. Could even replace the current user button as long as the rotation and press circuits are used. I think having a (Button RE Button) arrangement would make for a much improved user interface. Using RGB led backlit buttons could be an extra ‘wow factor’ as the rgb led can provide feedback / notifications. See this
Larger display - Possibly e-ink. Could be well worth the community effort to track down the ideal cost / size / quality / power required screen options. As well as it works I think there are several compromises made on the software and interface side due to the common, but small screens.
Temperature, Humidity, Pressure sensor - This would be a cool add on feature if it could be included for minimal additional costs. When these devices are used for relays this is often useful information for the node operator. But… It can also be useful for hikers to understand current environmental factors and with relatively simple code could show trends in changes and that is essentially a simple weather station that can be used to anticipate sudden changes in weather, like an incoming storm. For one of the original use cases, paragliding (and related flying) it is also very useful. Especially if we can use the SPI flash to store data logs.
Solar capable Battery Management System - It seems like for a small increase in cost a BMS that can accept usb and solar is possible. See this This can make solar charging much more accessible.