I mean it sounds like step one is to actually determine what she's concerned with - it sounds like you don't know.

You'll feel better about yourself if you go, that I guarantee

I wish I could say if we left the country we wouldn't have to worry about these things, but Europe is getting just as militaristic, fascist, end pro-Zionist. I think people are going to have to risk it and organize everywhere if we want a better life in the future. But that means some of them will get beat up, arrested, deported, imprisoned, or even killed as an example by the state of paramilitary groups. But then, the people before us made these very same risks and they must have had families and stuff who worried about them, too, but they did it anyway.

~~Maybe~~ definitely wear a mask.

Mask, faraday bag for phone, let them know your plan to escape if things go bad. They just worried about you so the key is to show how safe youll be.

Leave your phone at home, not in the car. If you take and wear a mask, never take it off.

Preferably don't go alone if you don't know anyone there.

Like MF_COOM said, first figure out what she has an issue with and then try to address it.

Dress in black block. Failing that, go to a yard sale/Goodwill/church resale shop for disposable clothing that are a generic and nondescript as possible. Maybe the only "flashy" item being a scarf or something that can (and will) be worn until you leave the protest and dispose of it along with the rest of the clothes. If there some cheapo running shoes or sneakers you can ditch, go for that as well.