Taproot keys are just the most updated version of bitcoin keys that we got in the last soft fork. Their capabilities are too much advanced beyond Segwit keys or older, still early, but at a minimum they can sign nostr events and own on-chain bitcoins! Soon they’ll be able to own Taro assets, open LN channels, and much more I’m sure. River has a good article on Taproot here: https://river.com/learn/terms/t/taproot/