Sum up kWh values of a week/months provided by another manufacturer sensor

Our Wallbox Pulsar Plus charger integration is a mess.

It does not even provide a simple kWh counter even though that is part of the api cloud where the data are coming from.

The only kWh sensor available is measuring “additional energy” for a charging session. Sounds weird. They meant to say “energy charged” or “energy delivered” but the were not able to use the translation available in the wallbox cloud.

Anyhow. This sensor looks like this

How can I add up all those session consumption figures in October to get a proper consumption figure of the wallbox for october displayed in Home Assistant ?

Right now I have nothing which is a shame considering that the WALLBOX integration has made it into the core of HA afaik.

I hope someone has an idea.

I have tried so far the statistic platform to sum it up for the past 21 days with a sampling figure of 21 but that result was crap cause at that point I was still believing that this would be a daily charging sensor which it is not, but a charging session counter.
And that makes it messy cause I had hoped that it is a daily counter and resets midnight, so 20 midnigth figures + todays consumption should equal the october consumption which is wrong due to the charging session as counter reset and not the daily consumption reset at midnight.