Glassware

What demonstrably matters: size and fill level. A glass large enough to swirl, filled no more than a third, releases far more aroma than a small glass filled to the brim. This is the single biggest glassware effect and it is free.

Also demonstrable: a narrow flute hides aroma. Sommeliers largely abandoned flutes for tulips because a flute preserves the bead at the cost of everything else.

Plausible: wider bowls suit delicate aromatic reds; narrower ones suit tannic reds. The effect is real but modest.

Mostly marketing: grape-specific glassware ranges. The claimed differences go well beyond what the evidence supports, and the gap between a good universal glass and a grape-specific one is far smaller than the gap between a good glass and a bad one.

If you buy one set, buy a decent universal tulip. It will do almost everything well.