In my sketches I had to define the below for the built in radio to even work:
#define MY_RF24_CE_PIN 10
#define MY_RF24_CS_PIN 9

Also, I have rf-nano's from 2 sources, the one I got from the first source (don't recall where it was from) doesn't send anything at all, according to the RasPi gateway*), the other 4 (from the 2nd source) just worked™

*) the radio initializes just fine, the gateway doesn't see any messages from it at all!...

The sketch looks like this now but does not work with gateway sketch (below). Is that related to code in the mysensors.h library, or do I need to make a change in the serial gateway sketch?

/*
  AnalogReadSerial

  Reads an analog input on pin 0, prints the result to the Serial Monitor.
  Graphical representation is available using Serial Plotter (Tools > Serial Plotter menu).
  Attach the center pin of a potentiometer to pin A0, and the outside pins to +5V and ground.

  This example code is in the public domain.

  http://www.arduino.cc/en/Tutorial/AnalogReadSerial
*/
#define MY_NODE_ID 35
// Enable debug prints
 #define MY_DEBUG
// Enable and select radio type attached
#define MY_RADIO_RF24
//#define MY_RADIO_NRF5_ESB
//#define MY_RADIO_RFM69
//#define MY_RADIO_RFM95
#define CE_PIN   10
#define CSN_PIN 9
#define CHILD_ID_A0 0
//#define CHILD_ID_A1 1
//#define CHILD_ID_A2 2
#include <MySensors.h>
MyMessage msg(CHILD_ID_A0, V_LEVEL);
//MyMessage msg2(CHILD_ID_A1, V_LEVEL);
//MyMessage msg3(CHILD_ID_A2, V_LEVEL);
// the setup routine runs once when you press reset:
void setup() {
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600);
}
void presentation()
{
  sendSketchInfo("Analog Soil Moisture Sensorx3", "1c.0");
  present(CHILD_ID_A0, S_MOISTURE);
 // present(CHILD_ID_A1, S_MOISTURE);
 // present(CHILD_ID_A2, S_MOISTURE);
}
// the loop routine runs over and over again forever:
void loop() {
  // read the input on analog pin 0:
 int sensorValue = analogRead(A0);
 //int sensorValueA1 = analogRead(A1);
 //int sensorValueA2 = analogRead(A2);
  // print out the value you read:
  Serial.println(sensorValue);
  // Serial.println(sensorValueA1);
  //Serial.println(sensorValueA2);
  send(msg.set(sensorValue));
  // send(msg2.set(sensorValueA1));
 // send(msg3.set(sensorValueA2));
  delay(10000);        // delay in between reads for stability
}

Gateway Sketch:

/*
  AnalogReadSerial

  Reads an analog input on pin 0, prints the result to the Serial Monitor.
  Graphical representation is available using Serial Plotter (Tools > Serial Plotter menu).
  Attach the center pin of a potentiometer to pin A0, and the outside pins to +5V and ground.

  This example code is in the public domain.

  http://www.arduino.cc/en/Tutorial/AnalogReadSerial
*/
#define MY_NODE_ID 35
// Enable debug prints
 #define MY_DEBUG
// Enable and select radio type attached
#define MY_RADIO_RF24
//#define MY_RADIO_NRF5_ESB
//#define MY_RADIO_RFM69
//#define MY_RADIO_RFM95
#define CE_PIN   10
#define CSN_PIN 9
#define CHILD_ID_A0 0
//#define CHILD_ID_A1 1
//#define CHILD_ID_A2 2
#include <MySensors.h>
MyMessage msg(CHILD_ID_A0, V_LEVEL);
//MyMessage msg2(CHILD_ID_A1, V_LEVEL);
//MyMessage msg3(CHILD_ID_A2, V_LEVEL);
// the setup routine runs once when you press reset:
void setup() {
  // initialize serial communication at 9600 bits per second:
  Serial.begin(9600);
}
void presentation()
{
  sendSketchInfo("Analog Soil Moisture Sensorx3", "1c.0");
  present(CHILD_ID_A0, S_MOISTURE);
 // present(CHILD_ID_A1, S_MOISTURE);
 // present(CHILD_ID_A2, S_MOISTURE);
}
// the loop routine runs over and over again forever:
void loop() {
  // read the input on analog pin 0:
 int sensorValue = analogRead(A0);
 //int sensorValueA1 = analogRead(A1);
 //int sensorValueA2 = analogRead(A2);
  // print out the value you read:
  Serial.println(sensorValue);
  // Serial.println(sensorValueA1);
  //Serial.println(sensorValueA2);
  send(msg.set(sensorValue));
  // send(msg2.set(sensorValueA1));
 // send(msg3.set(sensorValueA2));
  delay(10000);        // delay in between reads for stability
}