https://community.home-assistant.io/t/occupancy-blueprint/477772

occupancy.yaml

blueprint:
  name: Occupancy
  description: |
    This blueprint is based on the Wasp in a box princible. It is inspired by the AppDaemon app that does the same thing.

    You can find more information about this blueprint on the Home Assistant Community: https://community.home-assistant.io/t/occupancy-blueprint/477772
  domain: automation
  source_url: https://gist.github.com/AlexanderBabel/487f054b289b61f90afdc837d23cb85e
  input:
    door_sensor:
      name: Single Door Sensor or Door Sensor Group
      selector:
        entity:
          filter:
            - domain: binary_sensor
            - domain: input_boolean
    motion_sensor:
      name: Single Motion Sensor or Motion Sensor Group
      selector:
        entity:
          filter:
            - domain: binary_sensor
            - domain: input_boolean
    turn_off_delay:
      name: Motion Sensor turn off delay
      description: "Time after the sensor no longer detects motion to set the occupancy to clear. (Default = 5s)"
      default: 5
      selector:
        number:
          mode: box
          min: 0
          max: 3600
          unit_of_measurement: seconds
          step: 1.0
    motion_sensor_delay:
      name: Motion Sensor Delay
      description: |
        The time the motion sensor takes before clearning it's detected state. (Default=-1 [Disabled])

        I would recommend to add some extra delay to prevent false positives. E.g. If your sensor has a delay of 10 seconds set a delay of 12s.
      default: -1
      selector:
        number:
          mode: box
          min: -1
          max: 3600
          unit_of_measurement: seconds
          step: 1.0
    occupancy_helper:
      name: Occupancy Helper (Type input_boolean)
      description: This helper saves the occupancy state and can be used as a trigger of e.g. your light automation.
      selector:
        entity:
          domain: input_boolean
          multiple: false
    last_motion_helper:
      name: Last Motion Helper (Type date and time)
      description: This helper saves when the last movement was detected by the motion sensor or motion sensor group. This is necessary to prevent a false occupancy when you directly close the door behind you.
      selector:
        entity:
          domain: input_datetime
          multiple: false
variables:
  door_sensor: !input door_sensor
  motion_sensor: !input motion_sensor
  last_motion_helper: !input last_motion_helper
  motion_sensor_delay: !input motion_sensor_delay
trigger:
  - platform: state
    entity_id: !input motion_sensor
    from: "off"
    to: "on"
    id: motion
  - platform: state
    entity_id: !input door_sensor
    id: door_opened
    from: "off"
    to: "on"
  - platform: state
    entity_id: !input motion_sensor
    from: "on"
    to: "off"
    for: !input turn_off_delay
    id: clear
condition: []
action:
- choose:
  - conditions:
    - condition: trigger
      id: motion
    sequence:
    - service: input_datetime.set_datetime
      data:
        timestamp: "{{ as_timestamp(now()) }}"
      target:
        entity_id: !input last_motion_helper
    - if:
      - condition: state
        entity_id: !input occupancy_helper
        state: "off"
      then:
      - service: input_boolean.turn_on
        data: {}
        target:
          entity_id: !input occupancy_helper
  - conditions:
    - condition: state
      entity_id: !input occupancy_helper
      state: "on"
    - condition: or
      conditions:
      - condition: and
        conditions:
        - condition: trigger
          id: clear
        - condition: or
          conditions:
          - condition: state
            entity_id: !input door_sensor
            state: "on"
          - condition: template
            value_template: >-
              {{ is_state(door_sensor, 'off') and
              (as_local(as_datetime(states(last_motion_helper))) < states[door_sensor].last_changed and
              (motion_sensor_delay == -1 or (motion_sensor_delay > -1 and
                states[motion_sensor].last_changed - timedelta(seconds=motion_sensor_delay) <= states[door_sensor].last_changed))) }}
            alias: True, when the door is closed and last motion was detected before door was closed and no motion was detected in the timeout period
          alias: Check if door is open or closed and no motion was detected afterwards
      - condition: and
        conditions:
        - condition: trigger
          id: door_opened
        - condition: state
          entity_id: !input motion_sensor
          state: "off"
    sequence:
    - service: input_boolean.turn_off
      data: {}
      target:
        entity_id: !input occupancy_helper
  default: []
mode: queued
max: 10

Thank you for your suggestion. I added the improvement to the original gist :)