There are well documented and production-ready libraries that you can use to run your own servers with PHP alone, no need for fpm or mod_php. PHP's JIT is pretty impressive and you would be blown away by the results.

https://reactphp.org/

https://www.php.net/manual/en/book.ev.php

https://bitbucket.org/osmanov/pecl-event

https://www.workerman.net/