May I ask the BOM :)

Radio:

RAKwireless Store

WisBlock Starter Kit | WisBlock Basic Kit

WisBlock Starter Kit is a bundle of WisBlock Base RAK19007, WisBlock Core RAK4631, RAK11310 or RAK11200. You can choose your favorite WisBlock Core...

Charger:

Adafruit bq25185 USB / DC / Solar Lithium Ion/Polymer charger

We're always on the look out for better ways to make projects portable: being able to charge your battery in the most convenient manner will le...

(this one stops the charging if temperature is above 50C or bellow 0C to protect the lion battery, you need to solder a 10k thermistor to it) Solar panel: https://a.aliexpress.com/_Eve6B0g

Thank you ! (Can't zap you for some reason, I receive an error from your wallet's callback)