OK, but unfortunately, you are confusing the terms a bit here and you will probably only understand this if you delve a little into the history: CUBE packages were made available long before the introduction of the free GUI STM32CubeIDE and could not be installed in STM32CubeMX at that time. However, it was already quite easy to integrate the file structure of the CUBE package into one's own project, even those provided by external developers are often integrated in this way. Information on this can be found in UM2312, UM2385 and UM2388.
Newer CUBE packages from ST are then gradually made installable in CubeMX/IDE.
By the way, the X-CUBE-EEPROM package also contains sample projects for several families, which you can import and test directly from the extracted file structure.
Hope I could help a little?
Regards
/Peter