While this is good advice, it's not always very practical. OP indicated they are 17, meaning a minor. That may mean they need to be able to keep in contact with parents/guardians at home. I've also been to actions with groups of people where having contact is important for coordination.
If you need to bring a phone you can do so, but be mindful. Turn off any biometric features (fingerprint, face ID, etc). Police don't need a warrant to access your phone if you have biometrics. They can just put your phone in front of your face or put your finger on it to unlock. But if you have a passcode they cannot force you to unlock your phone without a warrant (and you can always just pretend you don't know the code).
I'd also suggest turning the phone off (or, at the very least, on airplane mode) except when you're actively using it. And minimize when you need it. I typically turn my phone off before arriving and wait until I'm gone from the location to turn it back on.
If you need to bring a phone, don't plan to do anything illegal. Large events like this will always have a significant segment of people who are not doing anything illegal at all. Stick with that group. Carry signs, chant, show your numbers, make contacts with other protesters in the crowd. But if/when you see people in black bloc, don't join them.
Completely agree. But I don't want to give people the impression that if they need to have a phone for whatever reason that they can't or shouldn't attend a protest, especially one like this where the point is to get as many people in the street as possible rather than achieving any specifically defined goal.
Leaving the phone at home is definitely the safer option, but I want people to know that they can still attend if they have to have a phone on them.