chromium/chrome/test/data/extensions/api_test/side_panel/api_only/manifest.json

{
  "name": "API only",
  "version": "0.1",
  "manifest_version": 3,
  "permissions": ["sidePanel"],
  "background": {"service_worker": "service_worker.js"},
  "description": "An example of dynamic side panel options, rather than static."
}