I believe if everyone who was against the current oligarchy started placing guillotine stickers everywhere, like you might for a favorite band, people would feel less isolated in their distaste for the current system.
And in an ideal world those who the guillotines are for might realize just how much they are in the minority.
We don’t need all of that iron age tech. Just go biblical and smash a rock down on their heads.
The power is in the symbolism: Brute violence targets one person. Clever messaging can reach far more. The guillotine has a history of dealing with oligarchs. That makes it a symbol easily recognised by people with a passing familiarity with the French Revolution and easily explained for those without: a tool for dealing with despots.
Of course we need to be wary to not also turn it into a tool of despotism, as it was further down the line, but that’s beyond “passing familiarity”.