Cannot read specific key from JSON file with Powershell - json

Question

I have a large JSON file (vehicle data) from which I want to read 1 specific value (vehicle identification number, for example). So, following this answer, I have this code with debug output:
$json = Get-Content $responsefilepath | ConvertFrom-Json
Write-Host $json
Write-Host $json.values | Where-Object key -eq "coc_VIN"
The first line puts my inputs file into an object;
the second line outputs the content of my file:
the third line should provide the value YV1DZ8256D2390218, but it's just blank.
On the PS command line, this provides a nice table of all values:
Get-Content .\data\02-returned\sample.json | ConvertFrom-Json
I would extend that command to filter on the desired key:
Get-Content .\data\02-returned\sample.json | ConvertFrom-Json | Where-Object key -eq "coc_VIN"
and again, that returns a blank line. Why?
Input file:

Answer 1

I figured it out myself:
Where-Object key presumes that there is a key/value pair where the name of the key is literally key. My data does not have that, so that's why it does not work.
Instead, I can use the dot notation to select the value of the key named "coc_VIN":
$json = Get-Content $responsefilepath | ConvertFrom-Json
$myvalue = $json.coc_VIN
...and that works!