Admin Tools as Separate App

I've been working on my SaaS app, and I'm starting to feel the pain of manually completing administrative tasks like onboarding new Users, bulk database changes, monitoring metrics, etc. I need to invest some time in creating a legit admin panel, if not just to ensure I don't miss any steps when I need to do some of these tasks.

However, I can't decide if I should build the admin tools as a separate app or build it right into the main app code.

Some places where the admin tools I need overlap with the tools I want to make available to organizational admins amongst the Users. This suggests that building the admin panel directly in the main app source code makes the most sense, but I'd like to hear other devs' experiences around this.