Thank you both for your answers, that clears up most of the confusion I had around that subject! For my first prototype I might go with the BM832 and a on board regulator like Nca78 mentionned.
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RE: [SOLVED] Nodes not receviving ACK from Pi3 gateway
Finally got some time to work on it. I started back from scratch, installing the openhabian image and configuring it all over. I problably made a mistake somewhere because now it does works well!