USB flash drives and external HD's work fine on my M1 iPad Pro. When you plug one in, it automatically shows in the files app just like Finder or Windows Explorer.
MS Office works fine on the iPad. I use Office 365, but any versions of Word, Excel, PP, Outlook from the App store will work. Apple also has its own free office sweet called
iWork which includes Pages, Number, and Keynote. A lot of people use and like iWork. And yes, the Google productivity suite (Docs, Sheets, etc.) are available on iPadOS also.
Here is a good article for the 10 Best Word Processing apps for the iPad.
You can use your iPad to edit documents, compile notes, or even crack out a novel. Here are the best iPad word processors for the job.
www.makeuseof.com