Development tools for Zephyr on STM32Workbench for Zephyr: VS Code extension to set up, build, flash and debug Zephyr applications on STM32.Devicetree manager: browse, edit and visualize Zephyr devicetree, STM32CubeMX-like for Zephyr.
Thanks! That works - I can build and debug.
The external builder also worked on my home laptop.
If you have any suggestions to determine why I have this problem, let me know. Meanwhile, I'll try a clean installation.