Switching from 32-bit Buster to 64-bit Bullseye made all the difference. The library and drivers were all built successfully without errors AFAICT, following the github instructions. I started from a plain Raspbian Bullseye release. The desktop looks a bit emptier than Astroberry. It does not have a network configuration GUI but at least VNC works fine.
I tried using the astroberry instructions for 64 bit, but I could not figure out how to work around an invalid website certificate.
Next, on to the Kstars and Ekos GUIs. Only then will I know if my camera will work - I nearly forgot why I am doing this!