I have a custom circuit using an off the shelf nRF52840 module that I am programming using Arduino and the ARM (Nim)BLE Boards > Generic nRF52840 target. So far have got down to a current consumption of 115uA between adverts. Below is a stripped down code that gets the same current figure, without adverts. nrf_power_system_off(NRF_POWER) gives below 2uA.