You can use any generic LoRa modem to send data.
To make things easy buy a card with the MCU & LoRa modem built in.
I would point you towards this unit here SODAQ ExpLoRer
This board is very special as it comes with three little gems
LoRa Microchip RN2483 Module
Bluetooth Microchip RN4871 Module
Cyptochip Microchip ATECC508A
You will need at least two SODAQ ExpLoRer for peer to peer with LoRa modems this is the minimum system you can run on. Then one of the SODAQ ExpLoRer would connect to your back-end systems. For this i would point you towards MQTT.