Considering https://community.home-assistant.io/t/homeassistant-number-how-does-it-work/842982/10 let's make the device independent from HA, i.e. add the possibility to dim the LED. The most intuitive way is perhaps a rotary button.

This can be done easily and just requires two GPIOs:

The code needs to be added to the sensor section.

sensor:
  - platform: rotary_encoder
    name: "Rotary Button"
    pin_a: GPIO4 #D2
    pin_b: GPIO5 #D1
    min_value: 0
    max_value: 100
    on_clockwise:
      - light.dim_relative:
          id: red_led
          relative_brightness: 5%
          transition_length: 500ms
    on_anticlockwise:
      - light.dim_relative:
          id: red_led
          relative_brightness: -5%
          transition_length: 500ms

The code is pretty self-explanatory.

This also turns up in the sensors field in HA. But to dim it from HA, the red LED needs to be clicked.