Now that I know what to look for, I found this from a BMW site for the Connected Cradle:
"Suitable for motorcycles equipped with factory and accessory option “Navigation Preparation”.
Not compatible with the “Navigation Prep.” equipped models that have an in-dashboard mounted docking station such as: R 1200 RT, R 1250 RT, and K 1600 series models.".
Genuine OEM Connectedride Cradle (77525a84266) for select 2017-2025 BMW-Motorrad motorcycles at an affordable price!
www.shopbmwmotorcycles.com
That leaves out liquid cooled RTs like mine.
There is also limited interface with the WinderlinQ interface, but it appears to me that the problem is that the RT and K1600 had limited data output for earlier models.