I honestly do not know why you are thinking of that. There’s also a previous thread I saw a long time ago whether Bitcoin should be a national currency or not. El Salvador made it happen so good for them.
In my own guts and instincts I certainly think Polygon as a national currency is impossible. Although I commend about their developments especially that I have been using them for a while in my DeFi transactions, they are not capable of being a “national currency”, given their own status like the market cap, worldwide adoption, etc.
As Bitcoin is already the OG and the most popular one, certain countries are already adopting it as legal tender. As for Polygon, I do not see it coming anytime in the future.
That will never happen because Polygon is an altcoin. This means Polygon is inferior to Bitcoin in terms of security/reliability/decentralization. Countries, and especially investors, want something safe and reliable. Bitcoin is the answer, because it's sound money that started it all. Without Bitcoin, none of the other coins would exist.
The only altcoin that might become a national currency (legal tender) after Bitcoin is Ethereum. That's because it's the second-largest cryptocurrency in market cap with a tried-and-tested blockchain network. Not to mention, ETH's ecosystem is the largest one available worldwide (after BTC). I'm fine with Polygon just the way it is as long as it doesn't turn into a "centralized shitcoin" in the long run. Who knows if it will live alongside BTC and ETH for generations? Just my thoughts