Thank you J. Reynolds for pointing me in the right direction!

I have used the following in "When the filter value is NOT available > provide a default argument > PHP Code"

$url = $_SERVER["REQUEST_URI"];
$url_path = parse_url($url, PHP_URL_PATH);
$basename = pathinfo($url_path, PATHINFO_BASENAME);
return $basename;

($basename is matching the last segment of the URL which is set via pathauto from a custom pseudo title field on my content type, and this field is also used the operational contextual filter in Views.)

Thank you J. Reynolds for pointing me in the right direction!

I have used the following in "When the filter value is NOT available > provide a default argument > PHP Code"

$url = $_SERVER["REQUEST_URI"];
$url_path = parse_url($url, PHP_URL_PATH);
$basename = pathinfo($url_path, PATHINFO_BASENAME);
return $basename;

($basename is matching the last segment of the URL which is set via pathauto from a custom pseudo title field on my content type, and this field is also used the operational contextual filter in Views.)

EDIT: I also have a Relationship "Content referencing Content from field_related_products" that is selected in the contextual filter.

Please refer to the answer from Ankit Agrawal for a better way to retrieve the URL