I have PLEX Pass but haven't set this up yet, not so sure about exposing my library to their service.
If this is the meta and worth it I will simply use it
I would avoid these at all costs. Things absolutely scream more than any server even you'll find and you need like 3 nuclear power plants to run them.
It's a good switch though, if you have a data center and power/cooling budget of a corporation
Easiest way with Portainer is to add it as a volume, then you can add the volumes to your container and add the folder in PLEX.
Point and click easy.
Not that I encourage it, but home users seldom pay MSRP for Windows licenses or at all. Getting around the licensing while ridiculously unlikely to get you busted is a hassle.
The answer is there's just better options you can install on top of Linux or BSD that are easier to manage, a better experience (nice web panels and not an RDP GUI or clunky thick client) and they have 0 licensing concerns to pay or work around.
I wouldn't host a share directly from the Linux CLI for some reason I always found this to be kind of a pain but it works, there's easy solutions like TrueNAS or OpenMediaVault, container based options and you can take the cowards way out with Portainer (that's what I do) to run tons of really lightweight services.
Windows is fine just not the best unless you're doing something that works better or needs it
Many clients including the mobile app hide, don't have or otherwise have the function to add a server via IP broken.
Why would I route through the internet and back to handle local traffic? That's the reason PLEX isn't in a DMZ