You can achieve this by adding HUD to your project. To do that, you can consider using widgets or you can get a little bit crazy and render the item in a different world.
On the widget approach, you can create an image for your item and fix it on any place you desire. Pretty straightforward.
Though if you want it to be affected by the lighting, you would need to keep the mesh, just don’t allow it to be collided with anything while always being visible to the player. I know for a fact that it’s possible since there are games that do exactly that, I personally don’t know how but found this post: [SOLVED] Rendering Meshes over everything