Maybe he could offer this "as a service" using LoRaWAN and a cheap Mikrotik basestation? As a backend Chirpstack can be used.

Not for 2400MHz LoRa.

For 433/868/915 they are great.

lol. 10.000km with a few bits of fixed-structure payload you mean.

Encoding basics

I'm currently thinkering of building a balloon with a 2.4GHz LoRa transmitter (SX128x) and a low-power STM32U microcontroller.

Why?

- You can repurpose 2.4GHz Wifi gear opening many doors

- You can easily include volunteers dumping data from HF into a IP sink for telemetry. TTGO offers boards with 2.4GHz LoRa.

- Theoretically you still can add a "low rate" 868MHz/433MHz and a "high rate" 2.4GHz for transmitting pictures and other stuff more quickly.

- BOM friendly. As the balloon might get lost you have to plan a bit for costs.

I've never seen a bigger network with Reticulum in the wild. And I'm deep into Mesh stuff with several local communities.

One of the main reasons of the communities not jumping onto the ship was that it's mostly a one-man-project and most of its Git changes are "Update" "Better Version" "Update" "Cleanup" which makes it basically impossible to track changes.