Hope this helps I demonstrate how to fire an MDX query directly: https://youtu.be/b_yeraBHJHw
If you want to list the Cubes and select them on the fly you would need to combine what I showed with a Reload or Partial Reload and you will need to build the MDX query string based on your selection, which means you will need another query that pulls the metadata about the Cubes.
There are 2 other videos that may help you with that.
Demonstration of pulling data on the fly from Snowflake using metadata about tables/dbs etc. https://youtu.be/63D0vCIUSp8
This 6 minute video where I show you the code of how to do a Partial Reload to add data, but retain everything already in the app. https://youtu.be/t7g_Hd3p0_A
