What is best/recommended way to handle "cross platform" paths?

[TraGicCode]

I have a command line application where i want to allow almost every command to accept a --config option. This will allow the user to specify a custom location in which the cli configuration file is located on their file system. By default, if this argument isn't passed, i would like it to default to the to a folder and file in the users home directory. On windows, [DefaultValue("~/.my-cli-app/config.yaml")] works like a charm. On linux, "~/.my-cli-app/config.yaml" is not a valid path.

I was able to get this to work using Validate() as shown below. This though feels wrong. Is there a cleaner better way to do this?

public class GlobalCommandSettings : CommandSettings
{
    // [CommandOption("--verbose")]
    // public bool Verbose { get; set; }

    [CommandOption("--config <FILE>")]
    [Description("Path to the config.yaml file to use for the CLI.")]
    [DefaultValue("~/.my-cli-app/config.yaml")]
    public string Config { get; set; }


    public override ValidationResult Validate()
    {
        if (Config == "~/.my-cli-app/config.yaml")
        {
            // Transform the default home path so it will work on linux appropriately
            Config = Path.Combine(
                Environment.GetFolderPath(Environment.SpecialFolder.UserProfile),
                ".my-cli-app",
                "config.yaml");
            Console.WriteLine(Config);
        }
        return ValidationResult.Success();
    }
}