PHPMailer attachment, doing it without a physical file

since that AddAttachment() function is expecting a path rather than byte data, you should do a php convert to temp file function and then pass that path string into your function

$prefix     = 'ConvertMediaArgs_'.time().'_';
$tempfile   = tempnam( $this->tempdir, $prefix );

// Args file create failure: kill script with TEMPFILEFAIL error
if($tempfile === false) {
    die('file could not be created');
}

// Write args as Key=Val (\n) to file
$fullpath   = $this->tempdir.$tempfile;
$content    = $someContent // <---------------- this is your file's data
$handle     = fopen( $tempfile, "w");
fwrite( $handle, $content );

// $fullpath is the path you wanna pass to your function
$xmail->addAttachment( $fullpath, $content );

AddStringAttachment($string,$filename,$encoding,$type)

eg

$mail = new PHPMailer();
$mail->AddStringAttachment($string,$filename,$encoding,$type);

https://phpmailer.github.io/PHPMailer/classes/PHPMailer-PHPMailer-PHPMailer.html#method_addStringAttachment