Pinning the entire document library is supported today. Learn more here, https://support.microsoft.com/en-us/office/add-a-sharepoint-page-or-list-to-a-channel-in-teams-131edef1-455f-4c67-a8ce-efa2ebf25f0b.
We currently do not support pinning a specific folder, but we are considering this feature.
An error occurred while saving the commentForrest commented
I also would like ability to add a Tab in Team that connects to Legacy SharePoint List.
Useful for a small Team to have access to a specific List on SP. Already have broken permissions on the legacy SP and granted Read permission to the O365 group of the Team. Just cannot get a List connector. Has Library and Documents but not granular to List only.