How do I modify Frappe Desk UI by changing HTML?

I’ve been told to rearrange and remove some of the UI for the sake of simplicity. I can hide some things with CSS but I have no idea how to edit the HTML

Not by changing HTML, because you won’t find one, but perhaps you’re looking for this:

https://frappeframework.com/docs/v14/user/en/desk/workspace/customization

link not working

I mean override the layout via my custom app on install. I’m already overriding some pages with it like the login page. But the UI for the sidebar and stuff is done via JS and views which I have no idea how to override properly

Have a look at the workspace docType

Is there any way I can override the JS files that make the sidebar etc

Okay editing the file directly works but it’s not a good way to do it. I guess I’ll have to override it somehow. Just moving the files to my custom app’s public folder is not working.

I’d like to know if there is a way to use a bundle from my custom app instead of from Frappe

You can add bundled js and css in hooks app_include_js and app_include_css