the battery module has no USB port and no charger IC. It gets charged from the M5Core2 (using the charger IC within M5Core2) when M5Core2 is powered via USB.

I do not have that LoRa module so I am afraid I cannot help you with questions related to that. Sorry.

Thanks
Felix

Given that I believe the GPIO do not conflict based on the referenced article, and with the caveat that power consumption and battery life is not yet a concern, does that stack look "complete" enough to get a "hello world" LoRa communication connection going between the M5 and a LoRa gateway?

I don't have a pile of parts and pieces from this ecosystem laying about, so I primarily want to know if that seems complete enough to power itself (however briefly) and simply send LoRa messages to a gateway.

Final stupid question: How is the battery charged? USB or something else?

This remains a question. Is there a charger for the battery module or is it a USB connection? You said that the Core2 has a built-in battery so that is helpful, thank you.

you probably won't get an authoritative answer here for a rather complex project like this.
But you could break it into smaller tasks and make some preliminary checks yourself.

• for instance check if the modules you want to stack do not have interfering GPIOs
• and if enough GPIOs are left to connect all the sensors you want
• or with an M5Core2 alone you could get an idea if the battery life is what you expect (the M5Core2 has a built in battery.)
• if you already have some sensors, check if the work with the M5Core2
• if you add the Lora Module you could check the Lora communication between M5Core2 and RPi. (Assuming you already have the RPi and whatever Lora shield is needed on that end.)

Again, the above is just a suggestion and is about how I'd tackle a project like this.

Thanks
Felix