Can helpers be nested too?

Yes, it is possible to nest helpers in subfolders in CodeIgniter. Here are the steps to do it:

Create a subfolder inside the "helpers" folder and name it whatever you want, for example, "subhelpers".

Create a helper file inside the "subhelpers" folder and name it with the same name as the helper class, for example, "Subhelpername_helper.php".

Inside the helper file, define the helper class using the subfolder name as a prefix, like this:
class Subhelpername_helper {
// Helper code here
}
In the controller, load the helper as usual, but include the subfolder name with a slash before the helper name, like this:
$this->load->helper('subhelpers/subhelpername');

This will load the helper from the "subhelpers" subfolder.

Note that you can nest subfolders inside other subfolders if you need to organize your helpers further. Just follow the same steps, but use the appropriate folder structure when loading the helper in the controller.