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.
No explicit effort It will generate FreeRTOS V9 source for you, It includes CMSIS_RTOS folder. I am not sure about drop-in replacement I just see same API defination.