I want to load a pre-built php page (and assocated scripts/styles/directories) as the front page. How do I go about this?

As shown in the template hierarchy image from the documentation, you can name your .php file as front-page.phpor home.php.

By default, WordPress sets your site’s home page to display your latest blog posts. This page is called the blog posts index. You can also set your blog posts to display on a separate static page. The template file home.php is used to render the blog posts index, whether it is being used as the front page or on separate static page. If home.php does not exist, WordPress will use index.php.

  1. home.php
  2. index.php

Note: If front-page.php exists, it will override the home.php
template.

See the image below:

enter image description here