A group of Microsoft Products and technologies used for sharing and managing content, knowledge, and applications.
Dear Éilis,
Thanks for your updates.
The workaround flow is similar to the flow you mention in the reference link. As the links of the list attachments doesn't work in Microsoft Teams, you can just copy the attachments into a site library and then create the sharing links for the attachments in Microsoft Planner automatically by using a flow in Power Automate. The key point is to use the Append to array variable connector with JSON code to drag all files' sharing links to one created task in Microsoft Planner and the links should be able to be opened in Microsoft Teams. However, it doesn't have thumbnails. Sorry for the inconvenience.
I create a list List A for users to add attachments and create a library Library A to automatically copy the attachments. The flow looks like the following.
Cliff