How secure are embedded/packaged models, textures, etc?

I have a client who is looking to build a VR project. But they are asking how secure the files will be, once packaged? Will anyone be able to dig out any of their proprietary licensed content and distribute it without their permission. It’s for a museum, so they just don’t want high resolution scans and textures from the art spread out publicly. Is this possible with Unreal?

You can’t get the asset as it is in your UE4 project, but it’s still possible to get the mesh and textures. Since UE4 is popular it is a target for tools to rip stuff out, but even besides that, there’s tools that can capture geometry and textures that are currently loaded into GPU memory while the program is running.
So ultimately, yes, the content can be taken out, but that’s going to be an issue no matter what 3D engine you use.
If the project is going to be on-site and not distributed online, then it won’t be a problem since people won’t be able to access the software. Online you also have the option to do something like Youtube VR where you render out images/video for VR so it doesn’t contain the actual 3D assets, just renderings of them.