You ever see those Wired videos where they talk about a concept on five different levels ranging from beginner to expert?

The first level answer is likely that, yes, you’re reasonably secure in your current setup. That’s true, but it’s also really simplified and it skips a lot of important considerations. (For example, “secure against what?”) One of the first big realizations that hit me after I’d been running servers for a little while and trying to chase security is the idea of a threat model. What protects me from a script kiddie trying to break into one of my web servers won’t do much for me against a phishing attack.

The more you do this, though, the more I think you’ll realize that security is more of a process than an actual state you can attain.

I think it sounds like you’re doing a good job moving cautiously and picking up things at each step. If the next step is remote access, you’ve got a pretty good situation for a mesh VPN like Tailscale or Netbird or ZeroTier. They’ll help you deal with the CGNAT and each one gives you a decent growth path where you can start out with a free tier and if you need it in the future, either buy into the product or self host it.