You have to use expo version of the crypto module.
expo install expo-crypto
more information is available here https://docs.expo.io/versions/latest/sdk/crypto/
For web3 there are other implementations in expo. Here is one for CRNA app. But comments include more details on to make it work on expo. https://gist.github.com/dougbacelar/29e60920d8fa1982535247563eb63766
CLICK HERE to find out more related problems solutions.