Today is November 26th, the official release day of the stable version of PHP 8. We are now including PHP 5.4, 7.1, 7.3, and 8 on our newest web hosting server.
The new update of Joomla 3.9.23 promises theoretical compatibility with PHP 8. Prestashop is not compatible at all. Wordpress should be compatible starting from version 5.6, which will be released on December 8th.