Somewhat related @frenck has a new custom integration of “things/features, that will never end up in Home Assistant itself”, as part of that there is a service recorder.import_statistics:
The description in the README.md is only “Advanced service to directly inject historical statistics data into the recorder long-term stats database.”
Without installing it to see the dialog from Developer tools → Services, the services.yaml gives some clues about parameters and how to use it:
recorder_import_statistics:
name: Import statistics 👻
description: >-
Import long-term statistics.
fields:
statistics_id:
name: Statistics ID
description: The statistics ID (entity ID) to import for.
required: true
selector:
entity:
name:
name: Name
description: The name of the statistics.
required: false
selector:
text:
source:
name: Source
description: The source of the statistics data.
required: true
selector:
text:
unit_of_measurement:
name: Unit of measurement
description: The unit of measurement of the statistics.
required: false
selector:
text:
has_mean:
name: Has a mean
description: If the statistics has a mean value.
required: true
selector:
boolean:
has_sum:
name: Has a sum
description: If the statistics has a sum value.
required: true
selector:
boolean:
stats:
name: Statistics
description: >-
A list of mappings/dictionaries with statistics to import.
The dictionaries must contain a "start" key with a datetime string
other valid options are "mean", "sum", "min", "max", "last_reset", and
"state". All of those are optional and either an integer or a float,
except for "last_reset" which is a datetime string.
required: true
selector:
object:
The code is here:
The code looks very straightforward/minimal and uses the recorder integration so it should be database agnostic.
There is this community thread for the Spook integration, but so far no clarifying details usage of import statistics: