Is this even legal? Can you refuse to give your phone to law enforcement? How can you protect your cryptocurrency wallet?
If the authorities are the ones who will ask you your phone, I guess you can refuse to give it to them. But if they have a search warrant or a court order for you to surrender your phone, then you cannot refuse it. Refusal means something like obstruction of justice or not cooperating to a lawful search or investigation. So the best way to safe keep your important information is not to store them in your phone.
That would be the case but we don't need to worry if we don't have any case since for sure we are still safe, but I don't think it's safe to store the details on our wallet and best to separate it the more safer place like putting it on desktop or maybe send it to another mail where people cannot reach it up.
Mails can usually prove dangerous in case of storing our wallet backups as mails could be leaked and it would directly endanger our wallets. Most secure way to store our cryptocurrencies is on offline storage so that they would always be safe. We can use only the amount we use for maybe trading or anything similar and store rest in our offline storage.
It is not necessary for the authorities to know our involvement in the cryptocurrencies or the blockchain technology as it might case some legal problems as involvement in cryptocurrencies is not yet legalized by most of the countries and it might seem like an illegal act so it is better we hide it from them.
Mails should never be an option for storing something very important as your backup file, PIN, or passwords, and other information. Offline storage is the best. And it should also be stored somewhere that could not easily catch the eye of anyone.
We do not necessarily have to hide our crypto involvement. In fact, we should begin to get out into the open and start showing support to crypto. But that should be limited to advocacy, or educating and informing people about Bitcoin and blockchain, but not about giving hints on your portfolio or wallets or Bitcoin holdings.