Hi Felix,
Confidentiality is a concern that many clients and developers bring up. As Yuri pointed out, you can host your application where ever you want, but that does not provide you with Confidentiality.
Keep in mind your project assets, gltf file, textures, JS, and everything that is displayed in your project is downloaded by the end user into their local browser and can be then taken use very similar to a JPG on a website. Not quite as easy as copy-paste but pretty close.
If your model is confidential….I would recommend streamlining it down and making it to the minimal requirements and removing any confidential elements. Once its released online the gltf file can be used for other projects and for other modeling needs. We often get requests to take security steps to make the use of the models more difficult. We break the model in to multiple parts and then load them in seperatelly making any one gltf unusable.
If confidentiality is important, minify your code, and wrap the application into a password protected area before you begin downloading assets so you can validate who is seeing it.
Just remember though…once someone has sceen it they have all they need. There is nothing confideintial that is displayed in a web browser.