Bug title

Describe the bug

Actually, when I'm calling NavigationView, the SelectedItem can't be accessed directly since it's protected. And when I try to use typeof with Navigate, it just shows the object as undefined. It feels really inconvenient, and the design kind of forces you to work with the structure they provided.

To Reproduce

Actually, when I'm calling NavigationView, the SelectedItem can't be accessed directly since it's protected. And when I try to use typeof with Navigate, it just shows the object as undefined. It feels really inconvenient, and the design kind of forces you to work with the structure they provided.

Expected behavior

Actually, when I'm calling NavigationView, the SelectedItem can't be accessed directly since it's protected. And when I try to use typeof with Navigate, it just shows the object as undefined. It feels really inconvenient, and the design kind of forces you to work with the structure they provided.

Screenshots

Actually, when I'm calling NavigationView, the SelectedItem can't be accessed directly since it's protected. And when I try to use typeof with Navigate, it just shows the object as undefined. It feels really inconvenient, and the design kind of forces you to work with the structure they provided.

OS version

Actually, when I'm calling NavigationView, the SelectedItem can't be accessed directly since it's protected. And when I try to use typeof with Navigate, it just shows the object as undefined. It feels really inconvenient, and the design kind of forces you to work with the structure they provided.

.NET version

Actually, when I'm calling NavigationView, the SelectedItem can't be accessed directly since it's protected. And when I try to use typeof with Navigate, it just shows the object as undefined. It feels really inconvenient, and the design kind of forces you to work with the structure they provided.

WPF-UI NuGet version

Actually, when I'm calling NavigationView, the SelectedItem can't be accessed directly since it's protected. And when I try to use typeof with Navigate, it just shows the object as undefined. It feels really inconvenient, and the design kind of forces you to work with the structure they provided.

Additional context

Actually, when I'm calling NavigationView, the SelectedItem can't be accessed directly since it's protected. And when I try to use typeof with Navigate, it just shows the object as undefined. It feels really inconvenient, and the design kind of forces you to work with the structure they provided.

Start with the NavigationView members named in the report, especially SelectedItem and Navigate, and reproduce the typeof behavior using the stated WPF-UI and .NET context. Before implementation, establish the expected public API behavior and provide specific version and environment details; the current report does not define a verifiable fix.