Nobody but you is saying "just give up" you're mischarachterizing others by adding that on there.
Protests can work, but they work via disobedience, inflicting other harms to those with power and (most importantly) threatening violence if things do not change. Anything that doesn't do all 3 of those things isn't a protest, it's a parade.
Parades can build community, but pretending parades are inherently some sort of engine of social progress is insane.
That's an incredibly whitewashed history you're going off of. It's not your fault, that's (very intentionally) the version of history that is taught within the US school system, but it is wildly inaccurate.
You're correct that the women's suffrage movement began in the early 19th century, but the 19th amendment didn't get passed until the early 20th century. It was a century (and arguably still counting) of men not just going “tut, tut, darling…” but using extreme violence, murder and sexual assault to try and supress any sort of equality. It took WW1 (and cross-pollinating with other global suffrage movements), a shift to a "deeds not words" approach, militant self defense and don't forget the women's suffrage and prohibition movements were tightly linked within the US (the 18th amendment passing just 2 years prior). Good luck characterizing the prohibition movement as any form of "nonviolent".
The "60s and 70s were rife with protests that made a difference, and they were peaceful" is a real nasty piece of, very intentional, amplification/veneration of MLK and deamplification/villification of everyone else. That's not to say he was ineffective, but the carrot doesn't work without there also being a stick.
If you're instead referencing the hippy movement, then even a cursory glance should be enough to realize those were not effective tactics and not anything you want to emulate...
If your focus is on the 60s-70s I highly recommend reading Kwame Ture's "black power" speech
So your plan for resistance within this scenario is to do what exactly? If the opposition is going to false flag violence like you are predicting here then doesn't that mean the only option for "harm reduction" would be to preemptively direct that violence towards said brown shirts?