You can share your files & folders on OneDrive or Sharepoint with other user & specify what level of access they get.
If your files & folders are in the Files section within a team or a channel in Teams then they are in Sharepoint. To open sharepoint select Open in Sharepoint from the menu within Files, sharing is then done the same as for OneDrive,
If you have access to shared files or folders you can access them from the web or from your file explorer
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