Powershell getting nested values: Can you use ConvertFrom-Json for nested Values

In order to report all leaf properties as name-value pairs (i.e. those properties that contain primitive JSON values as opposed to containing nested objects with properties and / or arrays), you need to recursively walk the object graph:

Find helper function Get-LeafProperty below; assuming you have already defined it, you can call it as follows:

@'
  {
    "Location": "EU",
    "Country": {
      "City": "xxx",
      "Town": "xxy"
    },
    "Transport": {
      "Train": "xxz"
    }
  }
'@ | 
  ConvertFrom-Json |
  Get-LeafProperty

Output (the display formatting of [pscustomobject] instances with .Name and .Value properties representing all the leaf properties):

Name     Value
----     -----
Location EU
City     xxx
Town     xxy
Train    xxz

Get-LeafProperty source code:

# Walks a potentially nested [pscustomobject] graph
# as returned by ConvertFrom-Json and outputs all
# leaf properties as name-value custom objects.
function Get-LeafProperty {
  param([Parameter(ValueFromPipeline)] [object] $InputObject)
  process {   
    if ($InputObject -is [array]) { # array as single input object -> recurse
      foreach ($o in $InputObject) { Get-LeafProperty $o }
    }
    else { 
      # Assumed to be a (potentially nested) [pscustomobject] instance:
      # Recursively process its properties.
      foreach ($p in $InputObject.psobject.properties) {
        if ($p.Value -is [array]) { # array -> recurse
          foreach ($o in $p.Value) { Get-LeafProperty $o }
        } elseif ($p.Value -is [System.Management.Automation.PSCustomObject] ) { # nested [pscustomobject] -> recurse
          Get-LeafProperty $p.Value
        } else { # leaf property reached -> output name-value pair
          [pscustomobject] @{ Name = $p.Name; Value = $p.Value }
        }
      }
    }
  }
}

Note: A variant of this function that outputs property name paths (e.g. Country.City) instead of just their names (e.g. City) can be found in this answer.