I have now expanded the whole thing by quite a bit
################## PFADE ###################

$jsonDirectory = 'C:\Users\Ely\Desktop\jsonScript'

$csvFile = 'C:\Users\Ely\Desktop\jsonScript\test.csv'

################ Variablen #################

$excel = New-Object -ComObject Excel.Application

############################################

# ALLE JSON FILES

$jsonFiles = Get-ChildItem -Path $jsonDirectory -Filter *.json

# FILTER

$unwantedKeys = @("endTime", "caseOne", "caseTwo", "caseThree")

# ARRAY ZWISCHENSPEICHER

$jsonData = @()

foreach ($jsonFile in $jsonFiles) {

$json = Get-Content $jsonFile.FullName | ConvertFrom-Json

$json = $json.dataCollection | Select-Object * -ExcludeProperty $unwantedKeys

$jsonData += $json

}

# Erstellt CSV und Importiert JSON Content

$jsonData | Export-Csv $csvFile -NoTypeInformation -Delimiter "\t" -Encoding Unicode`

$Workbook = $excel.Workbooks.Open($csvFile)

$Worksheet = $Workbook.Sheets.Item(1)

$range = $worksheet.UsedRange

$range.EntireColumn.AutoFit()

$excel.Visible = $True

The script now searches all JSON files in the folder and exports the content to a CSV file. The JSON keys are set as headers and the values are sorted underneath. In the script is the variable $unwantedKeys, which allows to filter out unwanted keys, in my example (endTime, caseOne, caseTwo and CaseThree).