Load ajax if is_home()

I want to show some simple things on homepage with ajax. The problem is I want to load everything when is_home() is true. Php, js, everything.

In funtions.php:

add_action('init', 'pint_functions_separation_test');
function pint_functions_separation_test(){
     if ( is_home() ) {
          require_once('functions_hometest.php');
     }
}

functions_hometest.php:

<?php
if (file_exists("./wp-load.php") && file_exists("./wp-blog-header.php")){
    define('WP_USE_THEMES', false);
    require_once("./wp-load.php");
    require_once("./wp-blog-header.php");
}

add_action( 'wp_ajax_nopriv_ajaxtest', 'ajaxajaxtest_handle_request' );
add_action( 'wp_ajax_ajaxtest', 'ajaxajaxtest_handle_request' );

function ajaxajaxtest_handle_request() {

  echo json_encode("evo me");

  die();

}
?>

JS:

<script>
jQuery(document).ready(function () {
    jQuery.ajax({
        url: '<?php echo admin_url( 'admin-ajax.php'); ?>',
        data: ({
            'action': 'ajaxtest',
        }),
        type: 'POST',
        dataType: 'json',
        success: function (data) {
            jQuery("#test_div_id").html(data);
        }
    });
});
</script>

WordPress on homepage loads functions_hometest.php but ajax returns 0.

And if I call php file just with

 require_once('functions_hometest.php');

everything works great, but I wan’t to keep loading of functions on bare minimum. Does that make any sense?

PS. I tried to call with

add_action('get_header', 'pint_functions_separation_login');

but i get the same results.

Thank you