Reload IConfiguration at runtime and have updated values on IOptionsMonitor.OnChange

[Ghevi]

Is there a way to add a json file to the configurations and update it at runtime? I don't need to have the file bundled in from the start.
But with this code reading the values from IConfiguration always return null.
Is it required that we use the AddJsonFile overload with new EmbeddedFileProvider(assembly) like in this issue?

    var fileName = "test.json";
    var basePath = FileSystem.Current.AppDataDirectory;
    var sourceFile = System.IO.Path.Combine(basePath , fileName);
    if (!File.Exists(sourceFile))
    {
        File.WriteAllText(sourceFile, JsonSerializer.Serialize(new AppSettings { ConnectionString = "start string" }));
    }

    var config = new ConfigurationBuilder()
          .SetBasePath(basePath)
          .AddJsonFile(fileName, optional: false, reloadOnChange: true).Build();
    builder.Configuration.AddConfiguration(config);
    builder.Services.Configure<AppSettings>(builder.Configuration.GetSection(nameof(AppSettings)));

The idea would be to retrieve this file later, change it and so that all the IOptionsMonitor.OnChange will be invoked.
The thing is that actually these callbacks get called but the values on these monitors (or from IConfiguration) remains always null

The only solution that works that I've found is setting the values manually like IConfiguration["AppSettings"] = {serialized value}

---- Update ----
So maybe I should have set the base path in the ConfigurationBuilder, but still values are always null.

[Ghevi]

Well dumb me 😊, the mistake is that using this line
JsonSerializer.Serialize(new AppSettings { ConnectionString = "start string" })
the file content will be {"ConnectionString":"start string"}

If i want this result {"AppSettings":{"ConnectionString":"start string"}}
i should do JsonSerializer.Serialize(new { AppSettings = new AppSettings { ConnectionString = "start string" } })

Woowiiee, i have the updated options in the optionsMonitor.OnChange callback now.

[Ghevi]

If anyone sees this, is there a way to store this file so it can't be access to the user? any tips?