@alex28 Hi Alex, sorry for your frustration.
I think documentation, either incomplete or outdated, is the crux of most open source projects.
I can not speak to the Hardware you used to try to get a network up as I have stuck to the more simple approach of using the simple Arduino ( ATmel328P) nodes for both sensors, repeaters and gateways, while using a RPI as the network controller with something like Domoticz running on it. I started years ago , even before the RFM069 was an option and made PCBs that incorporate the NRF24 and the ATMEL 328P along with the necessary voltage regulators etc. Maybe it was easier to get started then because there where less options and less misleading documentation was available, but I don't recall running into any problems worthwhile of mentioning or having the level of frustrations you have encountered.
I have two sites running with 8 and 12 nodes each. All sensors running on batteries. The range of the NRF24 is limited in that I only get through one or two sheet rock walls inside the house, but using the NRF24 module with the built in PA/LNA on the gateway and one repeater opened up the range considerably. I'm fairly positive that all the NRF modules I have a re clones....
I use the serial gateway on the Atmel328p and connect that directly to the serial port of the Rpi Zero-W, without USB adapters then run Domoticz on the PI to get onto the internet .
If you look on OSH - PCB you will find many good PCBs that you can make MYsensors nodes with using the more simple Arduino platform.
Most of my frustrations stemmed from the Linux configuration for the RPI so that it doesn't clobber the SD card on surprise power failure.
Cheers -- Gary