WP Wham Checkout Files Upload -- getting uploaded file info programmatically

functions.php

// which file uploader... i.e. "File Uploader #1" in the settings:
$file_uploader_id = 1;

// with the WooCommerce $order_id, we can get all the files for $file_uploader_id here:
$order_files = get_post_meta( $order_id, '_alg_checkout_files_upload_' . $file_uploader_id, true );

// $order_files will be an array. we can grab a specific file by key here:
$order_file = $order_files[ $file_key ];

// once we've picked a single $order_file, we can access it's 'tmp_name' (name it's stored under on the server):
$tmp_file_name = alg_get_alg_uploads_dir( 'checkout_files_upload' ) . '/' . $order_file['tmp_name'];

// ... or we can get it's "real" name (the original file name) here:
$file_name = $order_file['name'];