Is there a doc where I can learn how to listen to nft events?

Here is the documentation from Alchemy to listen to events for nft contract https://docs.alchemy.com/docs/how-to-listen-to-nft-mints

Also, some indexers support Polygon to index the data. For eg, Graph, Covalent

Here is the Polygon documentation for indexing the data 

https://docs.polygon.technology/tools/chain-indexer-framework/overview/?h=data+inde#the-solution-chain-indexer-framework