How to allow access only to index.php in the root of the site?

Question

PHP

The essence of the problem is as follows. It is necessary to forbid access to all *.php files on the server, except for the index.php file, which is located in the root directory only . The number of folders in the site root is unknown. It will not work to register .htaccess for each folder. Any ideas?

<Files *.php> 
  deny from all 
</Files>
<Files index.php> 
  allow from all 
</Files>

This option is not suitable: *.php files are not available, but index.php files are available in any folders

Answer 1

<FilesMatch "/index\.php$">