We also open sourced our module design (EE-02) that uses nRF52 as the MCU: https://github.com/ExploratoryEngineering/ee0x-hardware
You can buy the modules here, but I think stocks might be running low. (However, if anyone needs larger numbers of modules we can put you into contact with the factory we use for manufacturing them): https://shop.exploratory.engineering/
We work for a telco, and this was just a learning exercise to understand the opportunities and challenges with LPWA. While waiting for NB-IoT chipsets and network rollout. We mostly set up the shop to have a orderly way for people to get the devices from us if they want to experiment (free stuff has a tendency to end up lining people's drawers unused)
We built everything from (and including) the devices to the applications, and everything inbetween minus the LoRa gateway. The attitude being "okay we can read a bunch of datasheets and PPT-decks, but we're not going know anything unless we get hands on". So we did.
The modules were just to get the radio and MCU bits into a reusable module which we then used for about a dozen or so prototypes. We run Apache MyNewt on them (the EE-02 was actually used to develop LoRa support for MyNewt).
Since Nordic Semiconductor are in the same building the nRF52 was a pretty obvious choice (I think we might have been the first customer). They make lovely chips. And I'm not getting paid to say that :-).
We did think about building a gateway as well, but we felt it didn't add much to the exercise.
And now? Now we are doing the whole exercise again for NB-IoT, but this time it is to apply what we've learnt. That being said: we plan to open source stuff in the future. Both hardware and software.
The short version is that all the intelligence is in the Network Service. The gateways are mostly resposible for converting packets into RF and RF into packets. Gateways talk to the network service through some backhaul (ethernet, wifi, 4G etc).
(The Network Service is implemented in Go. The frontend is in a separate repository and done in vue.js)