Anybody with a router is likely setting up, or already has set up intelligence gathering tools.
As demonstrated in CHAZ, some clever folks set up free WIFI points around the area and snared quite a few ANTIFA/BLM/JBGC. They created a map of who was communicating with who.
OPSEC dictates probably the best strategy is to leave your phone at home, but nothing is perfect.
I would also take the time to encrypt your phone contents and set up an actual password, not face unlock or fingerprint. If you get picked up by LEO, remember your right to not self incriminate, enumerated in the Fifth Amendment.
Food and water would be essential items to bring with you, bring plenty for yourself and some to share if you want. A small first aid kit wouldn't be a horrible idea either.
Stay together, make plans and backup plans and rally points if you get separated from your group.
God bless you and be safe. I'll meet you all there.
EDIT: the comments here have excellent suggestions, I only watched a couple DEFCON videos a few years ago about WIFI activity being intercepted for intelligence gathering purposes. Heed the advice of people more knowledgeable than myself.
If you DO use biometric security on your phone, and you ever get pulled over by police, knows this:
A) You CAN be forced to provide biometric data to unlock it. Knowing this...
B) Hold the power button and turn off your phone (after recording anything/before handing over). When it restarts, it will require your password, which you CANNOT be forced to provide.
also, newer phones have an option you can turn on for a 4th power option where it disables non-password entry until after next sign in.