iOS runs on iPhones and iPads, are you saying you are using iPhones and iPads too? Or is this just on a Mac, with macOS?
The Mac includes the Finder, which much like Windows Explorer, shows all your files locally and any network locations and servers you have added to it.
click here ➜ Get to know the Finder on your Mac - Apple Support
iCloud also appears there.
One Drive would only show files stored on One Drive and nowhere else.
If you use Microsoft Office files, and if you need strict compatibility and support, then yes, Microsoft Office 365 would be the best option.
You can also use Apple's own Pages, Keynote and Numbers to open Microsoft office files but in some cases translation is not 100%, and may have differences in rendering specially if the files are using very specific Office features and layouts.
There are of course other apps, such as LibreOffice and OpenOffice that can open Microsoft files and are free.