Need help - vanity URL using PHP & NGINX.

Hi,

I have a small PHP & NGINX project that I am working on right now but my next goal is to clean-up the "URL".

Currently, the "URL" looks like this -> www.domain.com/user_id?=1. But I really want to clean it up and instead show the "@username" after the root domain like this -> "www.domain.com/@username".

If you have experience working on this kind of feature, your help is much appreciated :)

Thank you!