You could always wear a motorcycle helmet. But just a mask with sunglasses and a hat (something very common, like an unmarked bean) should do the trick. And of course, don't wear anything that has some special branding. Levi's and NorthFace are fine, but no local store, no phone numbers, no witty sayings.
Online is going to be problematic. It really depends upon how much someone decides to work in order to find you. Not sure what you are thinking of as far as “online” protest.
Contacting your legislators involves giving them your info to prove you’re a constituent. Posting angry social media comments (most common & least effective) depends upon the platform, but I work on the assumption any platform can - and will - turn over all info they have including location data.
Using anonymizers and all the hacker/spy tech to hide your identity is possible, but to accomplish what? If you are a WH insider planning to leak more than shitler already has, I suggest consulting a professional.
Still early in the thought process, but living in a deep blue state, things are going to have to get much worse before any significant or potentially risky protests take place within range.
Not sure what you are thinking of as far as “online” protest.
Posting angry social media comments (most common & least effective) depends upon the platform, but I work on the assumption any platform can - and will - turn over all info they have including location data.