Several PM2 web apps with NGINX

I have several NodeJS web apps running in localhost in different ports through PM2. I then use NGINX as web server.

I read the PM2/Nginx production setup for NGINX configuration

upstream my_nodejs_upstream {
    server 127.0.0.1:3001;
    keepalive 64;
}

server {
    listen 443 ssl;
    
    server_name www.my-website.com;
    ssl_certificate_key /etc/ssl/main.key;
    ssl_certificate     /etc/ssl/main.crt;
   
    location / {
    	proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Real-IP $remote_addr;
    	proxy_set_header Host $http_host;
        
    	proxy_http_version 1.1;
    	proxy_set_header Upgrade $http_upgrade;
    	proxy_set_header Connection "upgrade";
        
    	proxy_pass http://my_nodejs_upstream/;
    	proxy_redirect off;
    	proxy_read_timeout 240s;
    }
}

My questions are:

A) is there any further optimizations I can do in NGINX considering I have several NodeJS web apps running under PM2?

B) Can I load balance between different ports for the same app, considering the app runs in different instances?

Start with the linked PM2/Nginx production setup and the supplied NGINX upstream and server configuration. Determine whether the documentation should address optimization for several PM2 apps and load balancing multiple instances of the same app; done means providing clear, supported guidance for both questions.