Maybe you could persuade M5Stack to do a version of hardware that suits. Looks like maybe they do already for $40 if you combine a base and LORA unit - https:

Maybe you could persuade M5Stack to do a version of hardware that suits. Looks like maybe they do already for $40 if you combine a base and LORA unit - https://m5stack.com/collections/m5-core https://m5stack.com/collections/m5-core https://m5stack.com/collections/m5-module https://m5stack.com/collections/m5-module