Convert between DistinguishedName and CanonicalName

ConvertFrom-DN

#Updated ConvertFrom-DN to support container objects

function ConvertFrom-DN {
    [cmdletbinding()]
    param(
        [Parameter(Mandatory, ValueFromPipeline = $True, ValueFromPipelineByPropertyName = $True)]
        [ValidateNotNullOrEmpty()]
        [string[]]$DistinguishedName
    )
    process {
        foreach ($DN in $DistinguishedName) {
            Write-Verbose $DN
            $CanonNameSlug = ''
            $DC = ''
            foreach ( $item in ($DN.replace('\,', '~').split(','))) {
                if ( $item -notmatch 'DC=') {
                    $CanonNameSlug = $item.Substring(3) + '/' + $CanonNameSlug
                }
                else {
                    $DC += $item.Replace('DC=', ''); $DC += '.'
                }
            }
            $CanonicalName = $DC.Trim('.') + '/' + $CanonNameSlug.Replace('~', '\,').Trim('/')
            [PSCustomObject]@{
                'CanonicalName' = $CanonicalName;
            }
        }
    }
}

function ConvertFrom-CanonicalUser {
    [cmdletbinding()]
    param(
        [Parameter(Mandatory, ValueFromPipeline = $True, ValueFromPipelineByPropertyName = $True)]
        [ValidateNotNullOrEmpty()]
        [string]$CanonicalName
    )
    process {
        $obj = $CanonicalName.Split('/')
        [string]$DN = 'CN=' + $obj[$obj.count - 1]
        for ($i = $obj.count - 2; $i -ge 1; $i--) { $DN += ',OU=' + $obj[$i] }
        $obj[0].split('.') | ForEach-Object { $DN += ',DC=' + $_ }
        return $DN
    }
}

function ConvertFrom-CanonicalOU {
    [cmdletbinding()]
    param(
        [Parameter(Mandatory, ValueFromPipeline = $True, ValueFromPipelineByPropertyName = $True)]
        [ValidateNotNullOrEmpty()]
        [string]$CanonicalName
    )
    process {
        $obj = $CanonicalName.Split('/')
        [string]$DN = 'OU=' + $obj[$obj.count - 1]
        for ($i = $obj.count - 2; $i -ge 1; $i--) { $DN += ',OU=' + $obj[$i] }
        $obj[0].split('.') | ForEach-Object { $DN += ',DC=' + $_ }
        return $DN
    }
}

Thank you @shivtorov your latest update sent me down a rabbit hole wondering if there was a way to use what AD does to map names. With Pwsh making .NET calls possible, I came across DsCrackName and namespace calls like [System.DirectoryServices.ActiveDirectory.Domain]::GetComputerDomain() right in Pwsh. This led me to a COM object called NameTranslate that had code examples! I started writing new Pwsh based off the examples, then got smarter and found this gist - seems to work with whatever I toss at it, including your last example.

Convert-ADName.ps1

$myDN = Convert-ADName -Name [email protected] -InputType UPN -OutputType DN
$myCN = Convert-ADName -Name $myDN -InputType DN -OutputType canonical

$myDN
CN=\   \" 1 \+ 2 \" \= \< \#3 \> \; / \\  ~  \ ,OU=ServiceAccounts,OU=IT,OU=Departments,DC=contoso,DC=com

$myCN
contoso.com/Departments/IT/ServiceAccounts/   " 1 + 2 " = < #3 > ; \/ \\  ~   

$myContainer = 'contoso.com/Managed Service Accounts/it-mgdsvc'
Convert-ADName -Name $myContainer -InputType canonical -OutputType DN
CN=it-mgdsvc,CN=Managed Service Accounts,DC=contoso,DC=com