>>91122791
Ah, thanks, and it seems to drag-and-drop upload, the user must hold CTRL while doing so.
Modifications, only two lines, the last one with 'sdg' and the match include for "4channel...g":
// ==UserScript==
// @name 4chan /hdg/ catbox.moe userscript
// @namespace 4chanhdgcatbox
// @match https://boards.4chan.org/h/thread/*
// @match https://boards.4channel.org/g/thread/*
// @match https://boards.4chan.org/e/thread/*
// @match https://boards.4channe.org/vt/thread/*
// @grant GM.xmlHttpRequest
// @grant GM_xmlhttpRequest
// @version 2.4.2
// @author Anonymous
// @description Upload image directly to catbox.moe from 4chan
// @updateURL https://gist.github.com/raw/ca46eb79ce55e3216aecab49d5c7a3fb/catbox.user.js
// @downloadURL https://gist.github.com/raw/ca46eb79ce55e3216aecab49d5c7a3fb/catbox.user.js
// ==/UserScript==
(async function () {
const TITLE_CHECK = ['/hdg/', '>NAI LEAK SPEEDRUN', '/sdg/', '/vtai/'];