How do I acquire a complete list of all the VBA functions, VBA commands, VBA parameters, etc. available in Calc?
There is NOT any VBA or VB in the Calc nor in the LibreCffice. The Basic of the LibreOffice (StarBasic) has a good Help.
But there are thousands of the API functions in the LibreOffice what you can call from your Basic macro when you want to control the office suite by macros.
API: Application Programming Interface
That’s not true. Calc has a VBA compatibility layer. It’s not a complete VBA implementation and limited but many things work. See online help.
Did you intend to ask specifically about what is included by the
VBASupport statement, as @erAck wrote about? Perhaps you intended rather to ask about LibreOffice Basic runtime commands. Or you could be asking about UNO, the LibreOffice API.