Thanks for confirming this. Based on our knowledge, the STM32 SDKs have always supported FreeRTOS instead of RTX, so our project examples are based on it as well.
It does not mean that you cannot use RTX on STM32 projects, but you would need to setup the project manually, import the necessary source files and possibly change some sources to support STM32 hardware properly. We don’t provide any RTOS versions beyond the ones provided by the SDK vendors, but you should be able to find 3rd-party project examples online as the STM32 devices are very popular.