EKD - Ampere.StoragePro E3 with Ampere.IQ smartbox and REST api

Hello, I’m a newbie in HA and also in PV systems - but I have a PV system and also an a running HA on Raspberry since yesterday.
The PV systems answer on http request with a lot of different information via REST api.
If I send
Preformatted texthttp://MyIpAdress/rest/items/
I got following (json) feedback (reduced to one entry - overall 146 data):

{"link":"http://MyIpAdress/rest/items/foxesshybrid_battery_MySerial_battery_bms_1_soc","state":"54 %","stateDescription":{"pattern":"%.2f %%","readOnly":true,"options":[]},"editable":false,"type":"Number:Dimensionless","name":"foxesshybrid_battery_MySerial_battery_bms_1_soc","label":"#bms_1_soc","tags":[],"groupNames":[]},

In HA I added the configuration.yaml file:

# include PV sensor
homeassistant:
  packages: !include_dir_named integrations

and in integration folder I have a file with

rest:
  - resource: "http://MyIpAdress/rest/items/"
    scan_interval: 15
    sensor:
      - name: "Battery level"
        value_template: "{{ (value_json | selectattr('name','contains','battery_bms_1_soc') | list | first).state.split(' ')[0] | float | round(2) }}"
        unit_of_measurement: "%"
        unique_id: ampere_battery_stateOfCharge
        device_class: energy
        state_class: total

My questions :
Is this right?
Where can I find the SOC sensor value in HA?
How to implement this (and all other data) in the “Power Flow Card Plus”?
Is there anywhere already an implementation with these REST data and the (new) EKD system (–> there are foxess and also kiwigrid entries in the “Rest-answer” from system)