This is a bit odd....
Integration to Microsoft Teams will proceed in several stages. With the rollout of Microsoft Viva Connections for the Microsoft Teams desktop, we’ll begin introducing topic cards and highlights to Microsoft Teams in SharePoint pages integrated to the Connections desktop app for Teams. We’ll have more updates to Microsoft Teams integration throughout 2021.
The integration to Teams is only for Sharepoint pages shared through as yet unreleased integration that will show Sharepoint pages into a Teams app called Viva Connections.
I think you vastly over-estimate that people use Sharepoint pages, which is the only place Topics are surfacing, or in the search engine (which defeats the purpose of it supposed to be inline context sensitive help). Most people use Sharepoint documents and lists. Until Topics show up in the PC version of Word and PPT (NOT the web versions), Yammer, and in Teams chat, I see very limited value for Topics. The roadmap is pretty unclear as to when any of these "Experiences" might happen. I think an incremental price of $X per month per employee is going to deter people from using this too. It's not a separate product to end users and feels like you are just trying to make a revenue stream.
Hope to see more details about the roadmap and above points.