No those currencies are called representative currencies - the electronic digits you receive represent entitlement to some commodity stored somewhere. With physical commodities that are difficult to audit, this system was abused which led us to where we are today with "money" that banks print/type out of thin air and charge interest on as if they'd worked for it.
We can use anything as money, but some things work better than others. Unfortunately fiat currency works terribly as can be seen in the downfall of the modern society in the west. It enables a massive transfer of wealth to the people closest to the money printer from the general population. Look up "Cantillon effect"
They're still fiat because we agree on the idea that the gold itself is valuable. I cannot eat gold, plant it, power my home with it, or marry it. A gallon of water will keep me alive longer than an ounce of gold.
I understand that in dictionaries and textbooks we've defined that gold has value, but I'm pointing out that it has value because we AGREE it does because it's semi-rare and hard to get. Palladium is rarer, but cheaper, it's not as fun or pretty as gold.
Agreeing on the economic value of something does not make it fiat.
There's a big difference between something having ”economic value” and being something you value.
For example you probably value air - you'd die within minutes without it. But it's worthless - it has no economic value, because supply vastly outweighs demand.
I'd argue that Palladium is not as valuable as gold because there is not the same demand, because it's not as useful as money (harder to confidently recognise compared to gold)