I thought Thunderbird was an independent entity? Its still a subsidiary of the Mozilla Foundation but not directly a part of Mozzila such as Firefox or any of their other products. So stritcly speaking your data is with Thunderbied and not Mozilla.
this is at least how i understood their relation.




Not sure about one in particular, but check out the github page off guy called 11notes. He makes rootless and distroless images of popular applications. Might be something to find there ☺️