Here's a working UE-made portal gun created by a YouTuber.
A YouTuber known as Your Sandbox has managed to recreate a portal gun from Valve's legendary Portal game using Unreal Engine. The portals look and act very similar to the ones we could see in the original games, meaning they keep your flight speed when you fly through one of them and you are able to see through them. According to the author, the portals can be created in both Unreal Engine 4 and 5 using Unreal Blueprints.
Your Sandbox is a fantastic YouTube channel for those who are interested in Unreal Engine. The author shows how to recreate features and mechanics from other games using UE, Blender, Quixel Mixer, Houdini, etc. to add them to your own projects. So we highly recommend checking out this channel to learn more about Unreal Engine's capabilities.