As a temporary placeholder for a crypto wallet, POAPs can be reserved with an email address. Please note that reserving a POAP with an email address does not mint the POAP to the blockchain; minting to the blockchain can only be done with an Ethereum wallet. You can link your wallet to your email address at any time in the future to mint your POAPs to the blockchain (and, subsequently, store them safely within your Ethereum wallet).
Want a wallet anyway?
Be very careful not to send your POAPs to a wallet that you do not have direct control over, or does not connect with the Gnosis Chain (previously xDai), or else you will lose access to them forever.