Nice. But I’ll be surprised if you end up with a solution that has an “acceptable” battery life. That tends to be quite difficult to achieve even with a “aggressive deep sleep” set-up.
I think some people have similar solutions which involve using a “wake-up” pin (so wake up on pulse, send data, go back to sleep).
Did you see the ZigBee alternatives? There’s one listed here. I haven’t used it.
I don’t know about openthread so keen to hear how you go there.