Thank you for your votes and comments on this feature. The team is in the process of finalizing designs for deleting private chat threads. I will update as we have more progress to share.
The ability to delete Bot messages feature has been added to the backlog. Thank you for your feedback!
Thank you for your continued feedback. We are in the process of testing the downloading of the attendance report after the meeting has concluded. For status updates, please view the roadmap item here, https://www.microsoft.com/microsoft-365/roadmap?filters=Microsoft%20Teams&searchterms=66459.
Download of the meeting attendance list during a meeting is released for general availability. Please note this feature is turned off by default, and needs to be enabled via admin policy. To learn more, please visit our support page at https://support.office.com/article/download-attendance-reports-in-teams-ae7cf170-530c-47d3-84c1-3aedac74d310.