Did you ever try it? Where was the issues you ran into?
I mean, basically we do this all day. ^^ At least ppl who use flightsim.to to download freeware sceneries.
Probably half of the sceneries there require the usage of libraries for thirdparty objects, that have to be downloaded alongside the scenery.
The only important part is that the package has to be in the community folder, thats it. Then you can reference to those objects from the editor. Someone who has the package in the community folder sees the models, the others not.
There are probably other ways but this one is proven and works for hundreds of sceneries. I would go to flightsim.to and download one of the sceneries who do this (like mine, for example). I use models from the peoples library there in my project. And then you look at how the library is made. That should bring you one step closer ^^
Here is my airfield.
✓ EDMI-Flugplatz Illertissen is a Microsoft Flight Simulator 2020 mod created by Senchay. Download for free to enhance your experience in MSFS 2020.
flightsim.to
And for the full thing one needs this library installed
✓ Dave's 3D People Library is a Microsoft Flight Simulator 2020 mod created by BadMed. Download for free to enhance your experience in MSFS 2020.
flightsim.to
Just look at how this library is made. Maybe it helps ^^
Sorry, i didnt create a library myself yet but will soon. But it shouldnt be very complicated. You could create a project that has a modelLib with all your models. And this will be your library. All it needs is that this package is in community folder, like mentioned. Then you will see all those objects in the object brwoser in the MSFS Editor. Easy ^^