Nginx serve two services from same port from two files?

I have an nginx server file that serves some static content, looks something simple like:

server {
    listen              443 ssl;
    ssl_certificate     /etc/letsencrypt/live/this_host/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/this_host/privkey.pem;
    server_name static_content;

    # Proper rotation of session ticket encryption keys are not implemented, so
    # disable session tickets entirely
    ssl_session_tickets off;

    # Given that anticipated client devices are relatively modern, no need to
    # support insecure protocols
    ssl_protocols TLSv1.3;
    ssl_prefer_server_ciphers off;

    location /binaries/ {
        auth_basic "minimal protection";
        auth_basic_user_file /etc/nginx/auth/.htpasswd;
        root /var/www/static/;
    }

    location = /apple-app-site-association {
        alias /var/www/static/apple-app-site-association/apple-app-site-assocation;
        types { } default_type "content-type: application/json";
    }
}

I reuse this on a production server and a staging server. On the staging server, I want to front an API as well. If I just add another location in:

location ^~ /my_cool_api/v1/ {
    proxy_pass http://localhost:4000/my_cool_api/v1/;
}

But then I have different server files for the different serves, and it's poorly named as "static_content" at that point as well. I would like to make it more modular, so I tried leaving the first file alone, and adding a second file to the staging server:

server {
    listen              443 ssl;
    ssl_certificate     /etc/letsencrypt/live/this_host/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/this_host/privkey.pem;
    server_name my_cool_api;

    # Proper rotation of session ticket encryption keys are not implemented, so
    # disable session tickets entirely
    ssl_session_tickets off;

    # Given that anticipated client devices are relatively modern, no need to
    # support insecure protocols
    ssl_protocols TLSv1.3;
    ssl_prefer_server_ciphers off;

    location ^~ /accumulus_twig/v1/ {
        proxy_pass http://localhost:4000/accumulus_twig/v1/;
    }
}

This doesn't work though. After I link the two in sites-enabled, I just get the API working in that case, error.log shows that it can't find (static) files at /usr/share/nginx/html/binaries/. Is there not a modular way to have a single server definition at 443 with all of the proper certs etc, but define different location/matches in different files?

After reading the answer to this question (Use "include" in nginx server block but where to save?), I realized I could factor out my locations in a modular fashion via include files:

server {
    listen              443 ssl;
    ssl_certificate     /etc/letsencrypt/live/this_host/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/this_host/privkey.pem;
    server_name https;

    # Proper rotation of session ticket encryption keys are not implemented, so
    # disable session tickets entirely
    ssl_session_tickets off;

    # Given that anticipated client devices are relatively modern, no need to
    # support insecure protocols
    ssl_protocols TLSv1.3;
    ssl_prefer_server_ciphers off;

    include /etc/nginx/includes/*.location;
}

And then different locations can be added one-per-self-documentation-file.