1. 在Android项目的MainActivity.cs文件中添加以下代码，以请求摄像头和麦克风的权限：

public override void OnRequestPermissionsResult(int requestCode, string[] permissions, [GeneratedEnum] Android.Content.PM.Permission[] grantResults)
{
    base.OnRequestPermissionsResult(requestCode, permissions, grantResults);

    if (requestCode == 1)
    {
        if (grantResults[0] == Android.Content.PM.Permission.Granted && grantResults[1] == Android.Content.PM.Permission.Granted)
        {
            // 权限已授予，可以使用摄像头和麦克风了
        }
        else
        {
            // 权限未授予，无法使用摄像头和麦克风
        }
    }
}

2. 在Blazor MAUI的页面中，使用以下代码请求摄像头和麦克风的权限：

async Task GetCameraAndMicrophonePermissions()
{
    var requiredPermissions = new string[] { Android.Manifest.Permission.Camera, Android.Manifest.Permission.RecordAudio };

    if (!await Utils.CheckPermissions(requiredPermissions))
    {
        await Utils.RequestPermissions(requiredPermissions);
    }
}

public static async Task CheckPermissions(string[] permissions)
{
    var hasPermissions = true;

    foreach (var permission in permissions)
    {
        if (ContextCompat.CheckSelfPermission(MainApplication.Context, permission) == Android.Content.PM.Permission.Denied)
            hasPermissions = false;
    }

    return hasPermissions;
}

public static async Task RequestPermissions(string[] permissions)
{
    ActivityCompat.RequestPermissions(MainActivity.Instance, permissions, 1);
}

3. 确保在 Android 项目的Properties / AndroidManifest.xml文件中添加以下权限：