Three weeks later... Now customers from Batch 1 and 2 have received production units of the 16 laptop. Some valuable information about it is being revealed in the Framework community forums:
Being an AMD Advantage laptop, the Framework Laptop 16 has a MUX and supports AMD Smart Access Graphics (AMD equivalent of NVIDIA's Advanced Optimus.) Despite this there's no BIOS option to control the MUX for a dGPU-only option. This is probably to avoid being able to both control the MUX and remove the GPU module.
The BIOS doesn't have a lot of settings however, compared to for example a Lenovo Legion laptop (as seen in Jarrod's Tech video review)
It supports S0 sleep, S3 sleep, and hibernate
No confirmation thus far about being able to undervolt with either CPU option