you can try something like this:
$(function() {
// Add new Element in the selection action menu
$("#emp_ig_selection_actions_menu").menu("option").items.push({
type: "action",
id: "irHello",
hide: false,
label: 'hello world',
icon: 'fa fa-home',
action: function() {
alert("hello world");
}
});
// Disable Items in the Menu
apex.region("emp").widget().interactiveGrid("getActions").disable("selection-duplicate");
apex.region("emp").widget().interactiveGrid("getActions").disable("selection-revert");
});
To understand how the Menu Widget works, have a look here https://docs.oracle.com/database/apex-18.2/AEXJS/menu.html