Does a node for integrating with Tableau exist?
Not yet, but it might be possible to use the "external tools" nodes to that end, depending on how accessible Tableau is on the command line. There's one external tool node in the "Misc" folder and one in the "Labs" folder, with the latter beng more powerful, but more experimental as well. Alternatives may exist via R as well.
But I agree it'd be great to have a bespoke node for this, if only for marketing reasons. :-)
Cheers
E