ESPHome AHT20 Temperature and humidity custom component config using Adafruits AHTX0 library

ahtx0.h

// Put this in the ESPHome folder in your home assistant configuration

#include "esphome.h"
#include <Wire.h>
#include "Adafruit_AHTX0.h"

#define TAG "ahtx0"

class AHTX0Sensor : public PollingComponent {

  public:
    Adafruit_AHTX0 aht;
    Sensor *temperature_sensor = new Sensor();
    Sensor *humidity_sensor = new Sensor();

    AHTX0Sensor() : PollingComponent(15000) { }

    void setup() override {
        ESP_LOGCONFIG(TAG, "Setting up AHTX0Sensor...");
        if (!aht.begin()) {
            ESP_LOGCONFIG(TAG, "Failed to start AHTX0Sensor...");
        }
        LOG_SENSOR("  ", "Temperature", this->temperature_sensor);
        LOG_SENSOR("  ", "Humidity", this->humidity_sensor);
    }

    void update() override {
        sensors_event_t humidity, temp;
        aht.getEvent(&humidity, &temp);
        temperature_sensor->publish_state(temp.temperature);
        humidity_sensor->publish_state(humidity.relative_humidity);
    }
};

my-device.yaml

esphome:
  # ...
  includes:
  - ahtx0.h
  libraries:
    - SPI
    - Wire
    - adafruit/Adafruit BusIO@^1.14.1
    - adafruit/Adafruit Unified Sensor@^1.1.9
    - adafruit/Adafruit AHTX0@^2.0.3

# ...

i2c:

sensor:
  # ...
  - platform: custom
    lambda: |-
      auto aht20 = new AHTX0Sensor();
      App.register_component(aht20);
      return {aht20->temperature_sensor, aht20->humidity_sensor};
    sensors:
    - name: "Temperature"
      unit_of_measurement: °C
      accuracy_decimals: 2
    - name: "Humidity"
      unit_of_measurement: "%"
      accuracy_decimals: 2

Based on the code from esphome/feature-requests#1398 (comment)

Should work for everything supported by Adafruit AHTX0 (AHT10 and AHT20)