I have my services proxied through nginx and behind cloudflares free tier. That way I don’t have to worry about my IP getting exposed and opening myself up to DDOS/DOS attacks, which is a genuine threat if you do things that piss people off (I’m an admin on a popular minecraft server).

I would suggest signing up for a free Cloudflare account and setting up any DNS for your Pi through there, using the Cache feature.

Once that is done, setup an automated script that will pull down Cloudflare IPs into a file (you can use a cronjob to run this daily):

#!/bin/bash

set -e

cf_ips() {
  echo "# https://www.cloudflare.com/ips"

  for type in v4 v6; do
    echo "# IP$type"
    curl -sL "https://www.cloudflare.com/ips-$type/" | sed "s|^|allow |g" | sed "s|\$|;|g"
    echo
  done

  echo "# Generated at $(LC_ALL=C date)"
}

cf_ips > allow-cloudflare.conf
(cf_ips && echo "deny all; # deny all remaining ips") > allow-cloudflare-only.conf

Then in your web server config to only accept connections from Cloudflare IPs:

server {
	listen 80 default_server;
	listen [::]:80 default_server;
	server_name example.com;
        root /var/www/html;

	include /etc/nginx/allow-cloudflare-only.conf;
}

I prefer this method over UFW/iptables block as it allows you to control the IP block per web config, so if needed, you can make exceptions by not adding the include /etc/nginx/allow-cloudflare-only.conf; into that specific site’s conf file.

If you port forward to your Pi, only your Pi will be exposed. But, if your Pi gets pwned, it can in turn attack anything next to it. Safest is to isolate the Pi on it’s own subnet or a DMZ if your router has the functionality.

Of note, many home ISPs block standard server ports like 80 and 443. You might need to use non standard ports like 8080 and 8443

You could put the pi on its own subnet. That way if it’s hacked, the rest of the network is protected. Just make sure your router admin interface doesn’t answer on that subnet.

You are probably going to be ok unless someone really wants to hack you. The LastPass hack that exposed passwords of millions of people started from an open port in the home network of one of their engineers.

If you want to be somewhat safer, you could try something like the cloudflare tunnel thing to proxy your home network through their server.

I did this for some time. But now I don’t want any ports open at home.

That’s why I have a rented VPS that runs Traefik (a reverse proxy). This VPS has a VPN connection to my home net and is behind Cloudflare DNS. This is how I can safely expose services (even in my home net) to the Internet without forwarding any ports.

Of course those services need to have some kind of authentication.