I was able to get the KMeterISO to work with the Core.2 unit and using the Arduino IDE by doing the following:

• I needed to download the M5Unit-KMeterISO library from GITHUB - https://github.com/m5stack/M5Unit-KMeterISO

• I used the included "demo" example that was part of the library download but I had to make a few changes: I added a line "#include <M5Core2.h>" to the beginning. Added "M5.begin();" in void setup(), and finally changed the i2c pins from 21 & 22 to 32 & 33 in the kmeter.begin line - "while (!kmeter.begin(&Wire, KMETER_DEFAULT_ADDR, 32, 33, 100000L)) {"

Here is the complete modified demo example code:

#include "M5UnitKmeterISO.h"
#include <M5Core2.h>
#define INTERVAL_TIME 500

M5UnitKmeterISO kmeter;
uint8_t error_status = 0;
long delay_time      = 0;

long map(long x, long in_min, long in_max, long out_min, long out_max) {
    return (x - in_min) * (out_max - out_min) / (in_max - in_min) + out_min;
}

void setup() {
  M5.begin();
    Serial.begin(115200);
    while (!kmeter.begin(&Wire, KMETER_DEFAULT_ADDR, 32, 33, 100000L)) {
        Serial.println("Unit KmeterISO not found");
    }

    delay_time = millis() + INTERVAL_TIME;
}

void loop() {
    if (millis() > delay_time) {
        error_status = kmeter.getReadyStatus();
        if (error_status == 0) {
            Serial.printf("Celsius Temp: %.2fC\r\n",
                          ((float)(kmeter.getCelsiusTempValue())) / 100);
            Serial.printf("Fahrenheit Temp: %.2fF\r\n",
                          ((float)(kmeter.getFahrenheitTempValue())) / 100);
            Serial.printf(
                "Chip Celsius Temp: %.2fC\r\n",
                ((float)(kmeter.getInternalCelsiusTempValue())) / 100);
            Serial.printf(
                "Chip Fahrenheit Temp: %.2fF\r\n",
                ((float)(kmeter.getInternalFahrenheitTempValue())) / 100);
        } else {
            Serial.printf("Error: %d", kmeter.getReadyStatus());
        }

        delay_time = millis() + INTERVAL_TIME;
    }
}

KmeterISO unit is available in UIFlow2.1.2. Does it not work? (Note: I don't have that unit so I cannot test.)

If you want to run an I2C scan (internal and on port A) check out my example in the UIFlow2 Project Zone: M5Core2_I2CScan_Intern_PortA_UIFlow2.1.2

Thanks
Felix