Code sharing is not that trivial for number of reasons.
Best way to go is to start with all-out blinky app. Make sure it works with less than 2uA in sleep mode. Then add 1-by-1 all the features you need. Good exercise anyway. At least, this is what I’ve done when I needed to write firmware for another Lora E5 module device.
This time I’ve used AT-slave template for LoRaWAN part (instead of End Node), managed to make it low power without any problem. Already 1 month in the field and I do not observe any voltage drop on 2xAAA batteries. It has enabled AT-shell on LPUART for changing LoRaWAN keys etc.
You could also hire me if it is an option 
or write PM, maybe I can help you