Can the admins of my school-issued device see my Microsoft files if the system is based on Google?

I'm currently using a school-issued device, and I write a lot of fanfiction / short stories. Previously I've been using Google Docs [as it comes pre-installed on my device] with my school-provided Google account; but some of the content I've been writing about has been 'flagged' by my school's security system [they use Securly]. It's caused quite a few issues, and I don't want to continue getting in trouble because of my hobby for writing; especially considering I have no other way other than physical writing, which is a little bit of a hassle. I cannot use a different Google account on this device- the parameters don't allow me to sign into or out of any application that I wasn't already signed in on, meaning I'm not signed into any account on my browser, only on apps like Drive, Gmail, Classroom, and Docs.

Now, I also have a Microsoft account. This escapes the "no-other-Google-account" issue. My worry is that, because this device is issued and controlled by Securly and my school admins, they can still access my Word files despite it not being connected to Google in any way, other than the fact I'm using Microsoft Word in my browser and not the app. Is it possible for them to do so, and if so, are there any platforms I can use that won't be filtered or flagged by Securly?