Your guess as good as mine…
I sure hope so. It's a standard feature on the Ford Expeditions and Wagoneer/Grand Wagoneer and I'm about 51% sure it's a standard feature for the Toyota Sequoia. I'm not aware of that being a constraint for any of those other makes/models. Expeditions can be delivered in 2-3 months after ordering.
I'm not convinced it's a constraint for GM and it's disappointing to not have for a $70+k SUV. My theory is that GM is intentionally not including HD radio at this point.