How do you create a web app using three.js but standalone/without dependencies? - three.js

Question

I posted a similar thread:
How do you correctly include three.js and gltf.js?
Now that I've looked more into three.js and gltfloader.js, it seems there's a convoluted mix of packages and modules and imports and exports. My goal is to make an .html file, or web app, that will use three.js to put a 3D file over the user's face in the camera. I started off with Jeeliz's face filter repository, and modified it by putting the scripts (that it imported or had for) fully into the .html file. This worked for the cube, but then I realized I needed to use GLTFLoader.js to import a .glb file instead of the cube being over my face.
Now that I've looked into the repositories more, it's less clear how to completely include three.js and gltfloader.js into 1 html file. Every way I've tried (three.min.js and GLTFLoader.js copied into html file, three.js and GLTFLoader.js copied into html file, GLTFLoader.js copied into three.js which is also copied into the html file, and a few other ways) gives me Uncaught Error: GLTFLoader is not defined or Uncaught Error: THREE.GLTFLoader is not a constructor. I'm trying to use it in my main script with this
const loader = new GLTFLoader();
loader.load( '/your-glb-file2.glb', function ( gltf ) {
threeStuffs.faceObject.add( gltf.scene );
} );
but that first line is what is causing the error. Even when I copied the contents of GLTFLoader.js into the contents of three.js (which gave me ~37k lines of code), and copied that mega-script into my html file, it still gave me either of the 2 Uncaught Errors.
I Google'd how to use three.js with no dependencies, but it was going into package.json and npm stuff, even though I'm simply trying to copy three.js into the file itself. I couldn't find any guides on a "standalone" three.js web app, and I figured here is a good place to ask.
I know I can copy three.js into a script in an HTML file, but what I'm asking is how do I get GLTFLoader.js AND three.js into an HTML file and working so I can use
const loader = new GLTFLoader();
to load a glb file into the scene.
I've also tried
import { GLTFLoader } from '/GLTFLoader.js';
at the top of my "demo" script with GLTFLoader.js (from the correct current GitHub repository) in the same directory and it says "Cannot use import statement outside a module"
Thanks in advance!
EDIT:
Now I have tried a few more things, and it's like playing wackamole. At first I realized it's probably best to not combine revisions of three.js so now I've copied three.module.js into the folder and changed <script scr='../../libs/three/r112/three.js> to
<script type="importmap">
{
"imports": {
"THREE": "../../../libs/three/v112/three.js"
}
}
</script>
This got it to stop with some errors, but then it said the helper script is calling THREE and it's not defined. So I put
import * as THREE from 'path/to/three.js'
(of course with the correct path) and then it said the helper script is not defined in main.
I basically turned every script tag into a type="module" and imported three.js into each .js that needed it, and I keep running into errors, and it's becoming clear this is not the best way to set up three.js and gltfloader.js
Any help is appreciated.