A Raspberry Pi plus an external USB drive can serve as shared network storage for every device on your home network. the official tutorial walks through the full command-line setup.
The Raspberry Pi Foundation's NAS guide covers SSH connection, drive partitioning and formatting, Samba configuration, and accessing the share from macOS, Windows, and iOS. It assumes comfort with a terminal but no programming experience. This isn't a replacement for a dedicated NAS appliance if you need terabytes of data, but it's a solid way to share files locally and learn Linux basics in one project.
What would you store on a Pi NAS — documents, photos, media, backups?