I’m not going to write about what is Graal, others have done this better:
Nice article to read is also Top 10 Things To Do With GraalVM.
And its a good idea to join public Graal slack group as the devs and community is quite active and eager to respond.
From my experience you will need to ask for some advanced/hidden features as they are not described in docs or scattered between several sources. Advanced topics are described here: