Cross-Platform Device ID Snippet

I need a tiny ASP.NET Core web page that, when loaded in any modern browser on Windows desktops, Apple Macs, iPhones, and Android devices, immediately queries the machine or handset and shows its unique device identifier on screen—nothing more.

The solution has to be straight-forward to drop into an existing ASP.NET Core project: a single view and any required helper classes or JavaScript. Because browser access to native IDs is restricted, feel free to use whatever approach works best—WebAssembly, JavaScript APIs, or a short native-bridge plug-in—so long as it runs inside the ASP.NET Core app without additional installers on the user’s side.

Deliverables
• Complete, buildable ASP.NET Core project or clearly-organised code folder
• Any client-side script, plug-in, or NuGet package references required
• A brief README explaining how the ID is obtained per platform and how to wire the snippet into another project

Acceptance criteria
• Visiting the page on Windows, macOS, iOS Safari, or Android Chrome instantly shows a single, clearly-labelled device ID
• No extra user interaction beyond opening the page
• Code compiles and runs under the current LTS release of .NET Core