Microsoft teams

Share and collaborate
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You can share files and even entire folders without attaching anything. Send a link to the PowerPoint presentation you’re working on – and rest assured that everything else in your OneDrive will stay private. To share items from the OneDrive website, just select the item and select “Share

You would have to give your permission to share your files with others, they couldn't just start browsing. It is a very valid question though, I prefer to keep my files under my control rather than loading them to the Cloud, but that is just my paranoia