You can create an Ajax file for a specific template only, just mirror the path of your template in the mvc/ajax folder. For example, if you create a template my-template.php in a folder named “templates”, then your path to the Ajax file will be mvc/ajax/templates/my-template.php.
Here is the path to the sample: mvc/ajax/templates/template-sample.php in the Simpods Basic theme. You can always clone it and then customise to your needs.