internal/functions/resolve/Resolve-ResourceGroup.ps1

function Resolve-ResourceGroup {
    [CmdletBinding()]
    Param (
        [Parameter(Mandatory = $true)]
        [string] $InputReference,
        [Parameter(Mandatory = $true)]
        [string] $SubscriptionId,
        [switch] $Expand, # Return object { id, name }
        [switch] $DisplayName,
        [System.Management.Automation.PSCmdlet]
        $Cmdlet = $PSCmdlet
    )

    begin {
        $InputReference = Resolve-String -Text $InputReference
        $token = (Get-AzAccessToken -ResourceUrl $script:apiBaseUrl).Token
        if ($token.GetType().Name -eq "SecureString") {
            $bstr = [System.Runtime.InteropServices.Marshal]::SecureStringToBSTR($token)
            $token = [System.Runtime.InteropServices.Marshal]::PtrToStringAuto($bstr)
        }
    }
    process
    {            
        try {
            if ($InputReference -like '/subscriptions/*') { $resourceGroupId = $InputReference; $name = ($InputReference -split '/resourceGroups/')[1] -split '/' | Select-Object -First 1 }
            else { $resourceGroupId = (Invoke-RestMethod -Method GET -uri "$($script:apiBaseUrl)$($SubscriptionId.trimStart("/"))/resourcegroups/$($InputReference)?api-version=2022-01-01" -Headers @{"Authorization"="Bearer $($token)"}).id; $name = $InputReference }
            if (-not $Expand) { if ($DisplayName) { return $name } return $resourceGroupId }
            return [pscustomobject]@{ id=$resourceGroupId; displayName=$name }
        }
        catch {
            Write-PSFMessage -Level Warning -Message ("Cannot resolve Resource Group resource for input '{0}'. Searched tenant & desired configuration. Error: {1}" -f $InputReference,$_.Exception.Message) -Tag 'failed' -ErrorRecord $_
            $Cmdlet.ThrowTerminatingError($_)
        }
    }
}