WebGPU may still be in experimental mode and requires Unity 6000.1 or higher! This means you may need to enable experimental features, to use WebGPU
Enable “Show Pre-release Package Versions” under “Project Settings → Package Manager”
Now press the + button under Graphics API and add WebGPU. Make sure you move it to the top of the list. Leave WebGL2, since not all browsers (The more uncommon ones) support WebGPU at the moment.