I think you can just set the I2C pins in MyBoardNRF5.h without remapping the pins in MyBoardNRF5.cpp.
Look in MyBoardNRF5.h, under the Wire Interfaces section. Set SDL and SCA to 30 and 31 as appropriate for your board.
When you read the data sheet correctly you can see, that the distance between the pins is different for a AA and AAA battery holder. That`s why I was asking if somebody can recommend a holder that fits.
Hi @neelam, welcome to the forum!
The dimmer example should work. If you want to use only the esp8266 with wifi (no nrf/rfm or other radio), you'll also need to add gateway settings from https://www.mysensors.org/build/esp8266_gateway