I pretty much agree with you although I’d count protein and good fat supps as food. Apart from that there’s creatine.
I’m enjoying a mix of beta-alanine and arginine before training at the moment but it could be all placebo effect but if a ‘placebo effect’ gets you through a plateau then who cares. Placebo effects are real in a physiological sense after all. Just don’t spend the baby food money on this stuff.
With regards to elite pro athletes you’re right about research data. But you’ve got to ask why a pro who gets all there supps gratis would buy something expensive every month for years on end.