Scope of customizability of ERPNext Desk

I have an app XYZ installed in ERPNext. I wanted to know if I can edit the HTML elements like adding forms, buttons, and tables in desk pages. I know that the portal pages can be edited.

Only I was able to add an HTML table to the desk by appending a code to the frappe-bench>apps>frappe>public>js>frappe>views>workspace>workspace.js>workspace>show_page

I wasn’t able to find a similar folder structure in my XYZ.

Kindly help me. Is it feasible to do such edits?