WordPress One-Click Application Quickstart - whats going on here

I have been using your one click WP app for years now, starting with 14LTS to now 18LTS.

I use this for all of my WP setups because it is a decent setup that allows me to shave start up time.

Now you have added the Quickstart script and changed some of the default configuration in the vhosts. I would like to know how this is going to work with specific setups and what is happening with the setup.

Where is the $domain variable being pulled and how does that work. How does this affect custom vhost configurations and setting up my own SSL (I have sites that utilize wildcard ssl certs and subdomains that are created on the fly)

Moving this into production without more knowing what has changed is not responsible. I know the differences between 16 - 18 and where to get them, this new Quickstart though not so much.

I could investigate this more but hoping that someone can break it down for me or give me a link to more thorough documentation on the new Quickstart script.

Thanks!!