OpenSilver is not an emulator, a wrapper, or an Electron-style bundled browser. It is a complete reimplementation of the WPF/Silverlight API from scratch, using modern .NET, WebAssembly, and the browser's DOM.
On the Web, your C# code compiles to WebAssembly. Unlike canvas-based rendering approaches, XAML is rendered at runtime using real HTML elements: TextBox becomes <textarea>, MediaElement becomes <video>, PasswordBox becomes <input type="password">, Image becomes <img>, and so on. This unlocks native browser behaviors like Ctrl F search, text selection (to copy text), screen readers, SEO indexing, browser translation, mobile long-press, UI automated testing, and accessibility compliance. The compiled app is a set of static files (WebAssembly, JS, index.html...) that can be hosted anywhere: Azure, AWS, GitHub Pages, or any basic web server. No special server technology is required.
On desktop and mobile (via MAUI-OpenSilver Hybrid or Photino), the UI is still rendered as HTML/CSS, but C# runs as native .NET instead of WebAssembly. This preserves full compatibility with JS libraries and Blazor components (because the UI is still HTML/CSS), while adding native performance and direct access to platform APIs (because the runtime is native .NET).