Identify Plans from Groups

As Exchange/SharePoint admin, I'm cleaning up a bunch of orphaned groups in my tenant, and manually archiving any content. I have no easy way, that I'm aware of, of knowing if a group had a plan associated with it. Is there something I'm missing?

I'd like to simply see some sort of indication in either the M365 admin center, Exchange admin center, or SharePoint admin center, or even in the Azure admin center, that the group I'm about to delete had used Planner at some point. (If it had, I could then take ownership of the group and search the plan for content to archive, but to do that with every orphaned group would take ages!)