ODP Connect String with Oracle Wallet

I'm trying to use ODP.NET in PowerShell to access an Oracle DB. I want to use my existing Oracle Wallet for the connection credentials but I find no hints about how to specify the connect string with a Wallet. I've tried a few variations but I'm just not getting it correctly specified.

SQLPlus would use /@

What is it for ODP.NET?

Searching for the solution, I found that ODP needs to be configured to find the wallet. I specified the following as app.config:

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <oracle.manageddataaccess.client>
    <version number="4.121.2.0">
      <settings>
        <setting name="WALLET_LOCATION" value="(SOURCE = (METHOD = FILE)(METHOD_DATA = (DIRECTORY = c:\Users\xeaa2ll\Oracle\Wallet\)))"/>
        <setting name="SQLNET.WALLET_OVERRIDE" value="true"/>
        <setting name="TNS_ADMIN" value="c:\Users\xeaa2ll\ora\product\11.2.0\client_1\network\admin\"/>
      </settings>
    </version>
  </oracle.manageddataaccess.client>
</configuration>

The code I'm testing is

$configPath = "app.config"
[System.AppDomain]::CurrentDomain.SetData("APP_CONFIG_FILE", $configPath)

Add-Type -Path "c:\Users\xeaa2ll\ora\product\12.1.0\odp.net\managed\common\Oracle.ManagedDataAccess.dll"

$tns = 'OODBAP01'
$uid = 'xeaa2ll'
$pw  = 'xx'
$query = "select 1 from dual"
$connectionString = 'Data Source=/@oodbap01.bnymellon.net:1524:' + $tns  # fails
$connectionString = 'Data Source=/@' + $tns                              # fails
$connectionString = 'Data Source=' + $tns                                # fails
$connectionString = 'User Id = ' + $uid + '; Password = ' + $pw + '; Data Source=' + $tns
try {
    $connection = New-Object Oracle.ManagedDataAccess.Client.OracleConnection($connectionString)
    $connection.open()
}
catch
{
    Write-Error ("Can't open connection: {0}`n{1}" -f `
    $connection.ConnectionString, $_.Exception.ToString())
}
finally {
    $command=$connection.CreateCommand()
    $command.CommandText=$query
    $reader=$command.ExecuteReader()
    while ($reader.Read()) {
        $val = $reader.GetValue(0) 
        write-host $val
    }
}
if ($connection.State -eq 'Open') { $connection.close() }