I'm lost with what I'd need to do to access my server from outside my local network, and terrified of doing something wrong and leaving a hole open so any hacker can access my server. I'd like to do it some day, but I'd rather have a safe local network than screw and get my data stolen or deleted.
Setup a VPN via Wireguard or Tailscale. I personally have not done that but I have VPN setup through OpenVPN which I did not find that hard and people say that is significantly harder than Wireguard.
The other (less safe) option would be to setup a DMZ on your network for stuff you want to self host. That is a bit more involved though. I went through it for fun and setup a public Nextcloud instance along with DDNS and a reverse proxy. I was just messing around though and shut it down after testing performance.