Power Automate in Teams: Power Automate can be used to create scheduled cloud flows that automate repetitive tasks within Microsoft Teams. For example, a flow can be configured to run daily to post a reminder message in a channel or to create a task in the integrated Planner app.

Power Apps for Timesheets: Power Apps is a low-code platform designed for creating custom business applications. A timesheet application is a common use case, and such an app can be built and then embedded directly into a Teams channel or as a personal app for easy access.

Whiteboard Access for External Participants: External participants can collaborate on a Microsoft Whiteboard during a Teams meeting. However, their access is temporary and ends when the meeting concludes. For post-meeting access, the external user would need to be explicitly granted permissions to the whiteboard file, which is stored in the meeting organizer's OneDrive. By default, they do not retain access.

Microsoft Documentation, Power Automate: "You can do many things with Power Automate, including automating workflows between your favorite apps and services, synchronizing files, getting notifications, and collecting data... For example, you can create a cloud flow that saves an email attachment to OneDrive every time you receive an email from your boss." This includes scheduled flows that can interact with Teams. (Source: Microsoft Learn, "Get started with Power Automate", Get started section).

Microsoft Documentation, Power Apps in Teams: "With Power Apps, you can build custom apps to solve business problems that fit your team's needs. These apps can connect to business data stored either in the underlying data platform (Microsoft Dataverse) or in various online and on-premises data sources." A timesheet is a primary example of such a custom business app. (Source: Microsoft Learn, "Overview of Power Apps and Teams integration", Introduction section).

Microsoft Documentation, Whiteboard Sharing: "External and anonymous users will lose access to the board after the meeting ends... When a Teams meeting is recorded, a read-only link to the whiteboard is included in the meeting recording chat. This link is only accessible to the meeting attendees." This confirms that live collaboration access for external users ceases post-meeting. (Source: Microsoft Support, "Manage a whiteboard in Microsoft Teams", Share a whiteboard section).