@frob-0826 Do you want to find out the site collections that are associated with Microsoft Teams?
As you have SPO Admin permission, you can go to SharePoint admin center->Active sites, then filter all active sites by using "Connected to Microsoft Teams",then it will return all site collections connected to Microsoft Teams, like the image below:
Please have a try and check if it matches your requirement.
If I misunderstand your meaning, please feel free to reply.
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