For Chrome, you can swipe from the left edge to go back.api.onPageChange() and then get the page url.
import Component from "@glimmer/component";
import { apiInitializer } from "discourse/lib/api";
//import { iconHTML } from "discourse-common/lib/icon-library";
export default apiInitializer("1.14.0", (api) => {
api.onPageChange((url, title) => {
const allowedCategories = settings.allowed_in.split('|'); // Assuming this is a list of slugs
if (allowedCategories[0] != "") {
if (url.includes('/t/')) { // Check if we're on a topic page
const topicController = Discourse.__container__.lookup('controller:topic');
const topicModel = topicController.get('model');
const categorySlug = topicModel.category.slug; // Using slug for this example
if (allowedCategories.includes(categorySlug)) {
api.renderInOutlet(
'below-site-header',
<template>