Home Assistant blueprint for creating a mower offset, uses location and state to determine if it should update.

mower-offset.yaml

blueprint:
  name: GPS Offset for Mammotion or Other GPS Devices (Active Only)
  description: >
    Apply latitude and longitude offsets to a GPS device tracker (e.g. Mammotion mower)
    only when it is active (e.g. state = "mowing"). Useful for adjusting GPS
    alignment on maps without affecting idle locations.
  domain: automation
  input:
    source_tracker:
      name: Source GPS device
      description: The device tracker entity of your mower or GPS device.
      selector:
        entity:
          filter:
            - domain: device_tracker

    source_device:
      name: Source Mower
      description: The mower entity of your mower.
      selector:
        entity:
          filter:
            - domain: lawn_mower

    active_state:
      name: Active state
      description: >
        The state of the mower when it should apply the offset (e.g. "mowing", "working").
        Check Developer Tools → States for your device's actual value.
      default: "mowing"
      selector:
        text:

    latitude_offset:
      name: Latitude offset (meters)
      description: Offset in meters to apply to latitude (positive = north, negative = south).
      default: 0.0
      selector:
        number:
          min: -100.0
          max: 100.0
          step: 0.1
          unit_of_measurement: m

    longitude_offset:
      name: Longitude offset (meters)
      description: Offset in meters to apply to longitude (positive = east, negative = west).
      default: 0.0
      selector:
        number:
          min: -100.0
          max: 100.0
          step: 0.1
          unit_of_measurement: m

    new_device_id:
      name: New device tracker ID
      description: The device_tracker ID to create for the offset location.
      default: "luba_offset"
      selector:
        text:

mode: single

triggers:
  - trigger: state
    entity_id: !input source_tracker
    attribute: latitude
  - trigger: state
    entity_id: !input source_tracker
    attribute: longitude

condition:
  - condition: template
    value_template: >
      {{ states(source_device) == active_state or states(source_device) == 'returning' }}

variables:
  source_tracker: !input source_tracker
  source_device: !input source_device
  active_state: !input active_state
  latitude_offset: !input latitude_offset
  longitude_offset: !input longitude_offset
  new_device_id: !input new_device_id
  lat: "{{ state_attr(source_tracker, 'latitude') | float }}"
  lon: "{{ state_attr(source_tracker, 'longitude') | float }}"

actions:
  - action: device_tracker.see
    metadata: {}
    data:
      dev_id: "{{ new_device_id }}"
      gps:
        - "{{ lat + (latitude_offset / 111320) }}"
        - "{{ lon + (longitude_offset / (111320 * cos( lat * (pi/180)))) }}"
      gps_accuracy: "{{ state_attr(source_tracker, 'gps_accuracy') | int(0) }}"
      battery: "{{ state_attr(source_tracker, 'battery_level') | int(0) }}"