Thank you, Mister00X!
I did review the Debian wiki guidance. I am doubtful that this hardware is "optimus" -- it is newer and I think a different design. System76 has provided a command -- "system76-power" -- that is used to set the graphics chip to be used, and then the laptop must be rebooted to use the chosen graphics chip. I think their command is resetting a selection in the underlying UEFI, which is not user accessible in this system.
I will continue looking into it. Worst case, I will leave it Pop! OS and change to a KDE/Plasma desktop.
EDIT
On a siduction live USB stick, it loads the i915 driver.
Here is the graphics, running siduction live with inxi -G:
Graphics: Device-1: Intel TigerLake-H GT1 [UHD Graphics] driver: i915 v: kernel
Device-2: NVIDIA GA104M [GeForce RTX 3070 Mobile / Max-Q] driver: nouveau v: kernel
Device-3: Acer BisonCam NB Pro type: USB driver: uvcvideo
Display: x11 server: X.Org 1.20.11 driver: loaded: modesetting unloaded: fbdev,vesa resolution: 1920x1080~144Hz
OpenGL: renderer: Mesa Intel UHD Graphics (TGL GT1) v: 4.6 Mesa 21.2.1