I don't think that Matic can be called a hidden gem, because exactly what we have noticed about this coin and this network, This exactly has strong fundamentals with a promiisng network to compete with Ethereum. ALthough this still cannot beat Ethereum, at least, this can be one of the competitors that are really influencing.
It's hard to be sure that matic is for hidden gems because many other potential altcoins are reputable and have high chances for the future, but any coin can't be sure for long term development because we have had the worst history of Luna project, so I think ETH and BNB are gems true hidden and lower risk than other altcoins.
ETH and BNB, both are the brightest gems on the market and have been mined for a long time, they are no longer called hidden gems. The hidden gem here means many are unknown and likely to become like ethereum and the next bnb. To be honest, finding such gems is like finding a needle in the sea, currently we have more than 20000 coins and finding a highly profitable project is an impossible task. I think in addition to skill and experience, we need a little luck to find them.