Thank you @DrD123 for the reply and thank you @dohturdima for the link!
I’ve attached some images to show you all a bit more detail where you can see what the update was about and how it can’t be declined. You can also see the picture I took confirming the update was successful with the version number.
Everything with my car was fine before the update on Thursday so I can’t believe I’m the only user with this issue. It’s funny you mention not seeing 043-270 before and that was my initial hunch (there is a bug in this version). I’m not sure how common the USA model 2023 Legacy Premium with Navigation is (being an optional package) and I wonder if the configuration has some quirk different from the typical higher trim levels which contain navigation and something wasn’t fully tested against it. Because the update claims it was successfully installed and everything else appears to be working fine except with SiriusXM which was the core component of this update. And if a Factory Data Reset/Memory Initialization didn’t resolve…I’m not sure how the dealer presumably reinstalling the same software will fix it unless as mentioned they have access to another, updated, version or some way to blank everything/roll me back.