Welcome to the club! Gates are open. Come on in!!

FWIW, if you want to learn how to use the command line, docker, and how to manage and secure your services, I'd recommend installing Ubuntu server or Fedora server on the NucBox; and then install docker and learn how to get your services stood up using the docker cli.

This is the route I went specifically because I wanted to learn more about Linux, and how to manage a server and services.

The tools being offered as suggestions (unraid, truenas, yunohost) are abstraction layers meant to make hosting easier. And to be clear, there is nothing at all wrong with these tools or using them. What they'll do is give you a GUI to manage your system and services, making using the command line mostly unnecessary. Again, nothing at all wrong with that. Just depends on what you want.

Regarding exposing the services, it's good to be cautious. I went with Pangolin, which is like a self hosted version of tailscale/cloudflare tunnels (I'm simplifying a bit).

Pangolin allows you to access your services over a VPN tunnel, and, to set your desired level of authorization needed to access that service. I really like it and have found it to be very reliable.

Also, FWIW, I'm not in IT or an expert. Just a person who wanted to learn about Linux and self hosting to take back control from big tech.