I went through the free LoRa/LoRaWAN training from Semtech a couple years ago and it was very good at explaining how it works to non-experts.

https://learn.semtech.com/

IIRC, you might have to look up videos on thinks like OOK or preambles to understand those parts, but that's easy once you know what to look for and have the context of how it is used. 

 I mean the ax-25 packet radio protocol still used by some ham radio enthusiasts.

It went out of fashion, but its certainly not tied to a manufacturer. Something to consider.

That said , all the lora chips I use are chinese clones

https://en.m.wikipedia.org/wiki/AX.25