Why would two million people shaking keys be more impactful than the sanctions that have already devastated Russia's economy?
I don't particularly disagree with your stance, but I'm not convinced Russian protests will change anything more than external protests via sanctions have.
I still agree that Russians should be protesting anyway. Ukrainians are literally bleeding to death in their streets for Russian aggression, and anybody in Russia today should be protesting unless they support that.
You can make that argument for any repressive country and regime. Why do North Koreans not rise up? There is not much difference between Russia, Belarus and North Korea with regards to brainwashing of population and repression.
In Moscow there is no foreign influencer. It is 11 million Muskovites vs the Kremlin. Who would win that battle?
Even just 2 million people shaking their keys would send a message that Putin needs to change course.