Protest tip: Lock your phone with a passcode, not your photo/fingerprint
It's harder for police to access a phone with a passcode

"I was glad to see last week’s demonstrations for science included a safety manual with tips on how to prepare and how to respond if law enforcement got involved."
— Andrea Pitzer, March 11
Among the basic tips from Stand Up for Science protest safety: Wear practical clothing, charge your phone (if you're bringing it at all), and bring a bag with essentials like water and snacks.
A more advanced tip from the same list: If you usually wear contact lenses, swap them out for eyeglasses. Contact lenses will increase the eye irritation of pepper spray, should you encounter it, and would thus be a regrettable choice.
Also:
"Disable biometric authentication on your phone. Make sure the only way to unlock your phone is with a passcode, not with your face or your fingerprint. Legally, it’s more difficult for police to get into your phone if it’s locked with a passcode (vs. just holding up a confiscated device up to your face or against your fingertip)."