It would be really easy. I'm not sure why the author has gone through so much effort to hide what filter this is, but I'm assuming J2 is the blower power output and J3 is touchpad controls.

I've done exactly this on my own air filter, and it's about 200 lines of config. The hardest part is mapping binary outputs to a percentage:

    switch:
      - platform: gpio
        pin: GPIO21
        id: fan_low
        interlock_wait_time: 250ms
        interlock: &interlock_group [fan_low, fan_mid, fan_high, fan_turbo]
      - platform: gpio
        pin: GPIO25
        id: fan_mid
        interlock_wait_time: 250ms
        interlock: *interlock_group
      - platform: gpio
        pin: GPIO22
        id: fan_high
        interlock_wait_time: 250ms
        interlock: *interlock_group
      - platform: gpio
        pin: GPIO17
        id: fan_turbo
        interlock_wait_time: 250ms
        interlock: *interlock_group
    output:
      - platform: template
        id: fan_speed_output
        type: float
        write_action:
          - lambda: |-
              id(fan_low).turn_off();
              id(fan_mid).turn_off();
              id(fan_high).turn_off();
              id(fan_turbo).turn_off();
              auto light = ((AddressableLight*)id(status_light).get_output());
              for (int i = 6; i <= 9; i++) {
                light->get(i).set(Color::BLACK);
              }

              if (state < 0.24) {
              } else if (state < 0.26) {
                id(fan_low).turn_on();
                light->get(6).set(Color(255,0,0,0));
              } else if (state < 0.51) {
                id(fan_mid).turn_on();
                light->get(7).set(Color(255,0,0,0));
              } else if (state < 0.76) {
                id(fan_high).turn_on();
                light->get(8).set(Color(255,0,0,0));
              } else {
                id(fan_turbo).turn_on();
                light->get(9).set(Color(255,0,0,0));
              }
              light->schedule_show();

    fan:
      - platform: speed
        name: "Filter Speed"
        output: fan_speed_output
        speed_count: 4
        id: my_fan