Old PHP Project running PHP version 7.4 with Laravel 8 integration.

First of all thank you in advance for any assistance offered.

I have started with a company that has their site build in php 7.4 with a very large codebase (procedural php and not MVC) that has been built on for 14 years. They now realize that we need to drastically improve the site and upgrade it from 7.4 to the latest version.

A new feature has now been developed using Laravel by a separate company and my company wants to know if it would be possible to run the Laravel application inside their existing php application. The Laravel app/functionality was built in Laravel 9 and I created a Laravel 8 project and pulled in only what we need to the Laravel 8 project and it works. The Laravel 8 decision was made so as to accommodate the php 7.4 currently being used.

How, if possible in any way can I move this project into the existing project and access it through a url for example www.domain.com/v2

I had a look on Stack Overflow and Laracast, but most suggest converting the existing project to Laravel, but I cannot state how large the existing project is, we would need a separate development team just to do that. Others suggest editing the .htaccess and if any route on the existing php project returns a 404 it should try load the index.php in the subfolder where the Laravel project is.

I have a bit of experience with Laravel and PHP but I have never had to take a project from development to production.

Is this the correct approach and what are my options?

Any assistance would be appreciated. Thank you