A simple plugin that makes it possible to upload USDZ files in WordPress Media Manager

allow-usdz-in-wordpress-media-library.php

<?php
/**
 * Plugin Name: Allow USDZ mime in Wordpress Media Library
 * Plugin URI: https://gist.github.com/alexmoise/201a3b1196facb8343e82d0590f9b1ab
 * Description: A simple plugin that makes it possible to upload USDZ files in Media Manager. Don't forget to add the MIME type in web server config if necessary! No settings necessary, just activate and upload USDZ files in media library as usually. Tested with WP 5.2.3
 * Version: 1.2.81
 * Author: Alex Moise
 * Author URI: https://moise.pro
 */

function mos_filter_fix_wp_check_filetype_and_ext( $data, $file, $filename, $mimes ) {
	if ( ! empty( $data['ext'] ) && ! empty( $data['type'] ) ) {
		return $data;
	}
	$registered_file_types = ['usdz' => 'model/vnd.usdz+zip|application/octet-stream|model/x-vnd.usdz+zip'];
	$filetype = wp_check_filetype( $filename, $mimes );
	if ( ! isset( $registered_file_types[ $filetype['ext'] ] ) ) {
		return $data;
	}
	return [
		'ext' => $filetype['ext'],
		'type' => $filetype['type'],
		'proper_filename' => $data['proper_filename'],
	];
}

function mos_allow_usdz( $mime_types ) {
	if ( ! in_array( 'usdz', $mime_types ) ) { 
		$mime_types['usdz'] = 'model/vnd.usdz+zip|application/octet-stream|model/x-vnd.usdz+zip';
	}
	return $mime_types;
}
add_filter( 'wp_check_filetype_and_ext', 'mos_filter_fix_wp_check_filetype_and_ext', 10, 4 );
add_filter( 'upload_mimes', 'mos_allow_usdz' );

?>