NGINX configuration

Hi everyone!

I am making a social site.
I want the user’s profile to be visible at https://example.com/<username>

I want to create a username.php file to show the profile based on the username.
And then use NGINX to resolve the URL to that file?

How can I achieve this? I am not using any frameworks.
My current NGINX config -

server {
    listen 80;
    index index.php index.html;
    error_log  /var/log/nginx/error.log;
    access_log /var/log/nginx/access.log;
    root /var/www/;

    
    location /message {
    rewrite ^/message/(.*)$ /message.php?id=$1 last;
    }
    
    location ~ \.php$ {
        try_files $uri =404;
        fastcgi_split_path_info ^(.+\.php)(/.+)$;
        fastcgi_pass app:9000;
        fastcgi_index index.php;
        include fastcgi_params;
        fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
        fastcgi_param PATH_INFO $fastcgi_path_info;
    }
    location / {
        try_files $uri $uri/ /index.php?$query_string;
        gzip_static on;
    }
}

Here app:9000 is the local network created by docker compose

I did some googling, I think it can be done using the last server block, but then how will I show 404 errors for static files?