WrapperFunctionForJson.ps1

function ConvertFrom-JsonToProcess
{
    [OutputType([System.Diagnostics.Process[]])]
    [CmdletBinding()]
    param
    (
        [Parameter(Mandatory = $true, ValueFromPipeline = $true)]
        [string]$Path
    )

    process
    {
        cat $Path | ConvertFrom-Json
    }
}

WrapperSample.ps1

ps | select -First 2 | ConvertTo-Json | Out-File .\hoge.json
ConvertFrom-JsonToProcess -Path .\hoge.json | %{$_}