The sample projects for each device family generally come from the SDKs provided by the device vendor and their amount depends on the popularity of the specific device family. E.g. the STM32 SDKs come with numerous examples and frameworks and are very popular, so VisualGDB offers many examples in the project wizard and encapsulates many frameworks from the SDKs. The Tiva SDK is much simpler and the devices are less popular than STM32, hence the examples offered by VisualGDB are simpler.
The easiest way to get FreeRTOS on Tiva devices would be to download the Tiva C SDK (please use the same version as the VisualGDB’s BSP) and manually add the files from third_party\FreeRTOS\Source to the project (you would need to ensure that only one port instance and one heap instance is selected).