Local storage manager after the example as found in https://gist.github.com/roydekleijn/5073579

LocalStorageManager.cs

using OpenQA.Selenium;

//Did not yet test this code
//I'll update if needed (and if I think of it), but this is the gist of it (pun intended)
namespace LocalStorageManager
{
    class LocalStorageManager
    {
        private IJavaScriptExecutor js;

        public LocalStorageManager(IWebDriver driver)
        {
            this.js = (IJavaScriptExecutor)driver;
        }

        public void RemoveItemFromLocalStorage(string item)
        {
            js.ExecuteScript(
                $"window.localStorage.removeItem'{item}');"
                );
        }

        public bool IsItemPresentInLocalStorage(string item)
        {
            return !(js.ExecuteScript(
                $"return window.localStorage.getItem('{item}');") == null);
        }

        public string GetItemFromLocalStorage(string key)
        {
            return (string)js.ExecuteScript(
                $"return window.localStorage.key('{key}')");
        }

        public string GetKeyFromLocalStorage(int key)
        {
            return (string)js.ExecuteScript(
                $"return window.localStorage.key('{key}')");
        }

        public long GetLocalStorageLength()
        {
            return (long)js.ExecuteScript(
                "return window.localStorage.length;");
        }

        public void SetItemInLocalStorage(string item, string value)
        {
            js.ExecuteScript(
                $"window.localStorage.setItem('{item}', '{value}');");
        }

        public void ClearLocalStorage()
        {
            js.ExecuteScript(
                "window.localStorage.clear();");
        }
    }
}