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.
To see the disassembly you should switch to Instruction Stepping Mode by clicking th esmall icon on the top right of the Debug view (or just on the right of the "step" buttons.