Gold is never free to store, so you will always have to pay a premium to "own" it. This premium might be hidden, but it's always going to be there. If you're storing it yourself, that would be in the form of safes and transportation risk, or insurance. If someone else is holding it for you, there might be fees, or exchange premiums, but those fees will be there.

Also, if gold is used to back a crypto, it can't be trustless. You're going to have to just trust the person holding the gold, that it's actually there. If it isn't, once found out, the currency you're holding goes to zero.

Just my 2 satoshi.