Of course Polygon can rival with BSC, because Polygon has become one of the most popular blockchain at this time, moreover gas fees from Polygon are also very cheap and that's what attracted many projects to using Blockchain from Polygon, therefore I believe Polygon can be the toughest rival of BSC in the future.
we have to admit that the BSC is very good at this time and is supported by the exchange itself so that it is possible to make innovations that can make it easier. bsc is still in the process of being considered as an alternative to erc20 and even then, it will take time for people to believe in using it. so I think it's still too early that polygon will be able to compete with bsc, let time decide because there are also many other platforms that exist and will still compete in crypto.