I started work to do point to point communications using the previous version of Nordics short-range 2.4GHz chip the nRF24 series. That is cheap and can be connected to an Arduino simply. However, after getting myself in software tangles with state machines trying to keep the tx and rx in sync, switching directions of transmission, trying to (re)-invent pairing, I discovered that much of that work had already been done by Nordic in the nRF52 SDK and libraries AND, because the chip can contain my own developed programs, meant that everything could be done in one SOC. That, together with the issue of obsolescence, made me drop the nRF24 line promptly.
I then started with the nRF52832 which was widely available (both HDK and third party modules) and re-wrote the software to use the GZLL proprietory point to point protocol software of Nordic Semiconductors. Unlike my software on the nRF24, the Nordic software worked.
Right now I am working with the nRF52840. One of the first things I did was to do my own documentation of the connections so I could see what I was doing more clearly. If you want to see and/or use this work, you will find it here .