Thank you for your feedback! Contextual search within a specific chat or channel, filter options for messages, files and people are all available in the product today.
To learn more, please visit https://support.microsoft.com/office/search-for-messages-and-more-in-teams-4a351520-33f4-42ab-a5ee-5fc0ab88b263.
This item remains on the backlog.
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.