Not all countries are buying oil and gas in rubble, just the ones russia considers “unfriendly”. But even from those, russia isnt enforcing it. Germany has said it wouldn’t pay in ruble. US doesn’t buy anything from Russia. Hungary is paying in ruble.
By paying in ruble they create an artificial demand for the currency, making it worth more. However Russian government can make the same thing with the euro / dollars they receive from oil / gas purchase. The only reason they asked others pay in ruble is so they don’t have to do the conversion themselves because you know, with all the sanctions it is a pain to do it.
The price spikes in Russia didn’t go back after the currency stabilized, so regular Russians are still screwed
I’ve never seen anything about the gold standard thing, but even if it is true 1- gold price is also volatile and 2- there is a reason people moved away from gold standard