The Mobilizon product reflects these beliefs with interesting features, like the ability to register for events using different identities but under one account. So you could, say, sign up for a protest using a different profile than the one you use to register for your dad's birthday party — that way what should be a lighthearted celebration doesn't turn sour as you fight with your parents over your political activism.
Mobilizon is also completely distributed, meaning anyone can install the software on their own servers and dictate their own rules for participation. Each instance has a page outlining its rules and data collection practices so you can decide for yourself whether you want to create an event or group there. Different instances of Mobilizon can be connected, if the operators choose, so that events and accounts can be shared across them.
Fighting the good fight — Distributed alternatives to the major social networks have popped up from time to time. Diaspora is the same concept for replicating all of Facebook. And there's Mastodon for Twitter. PeerTube is an alternative to YouTube.
None have exactly broken those company's grip on power because economies of scale still dictate that people use whatever service their friends are already on. But there definitely won't be alternatives if nobody tries, so it's good to see people out there at least attempting to build compelling products to challenge the major platforms.
Recent instances of Zoom shutting down political discussions highlights the place we're at today, where the major platforms are being pulled in every direction and hopelessly trying to appease everyone. But their sheer scale means they're in a losing battle, and one faction or another will always be harmed. Even in the likely case that Mobilizon doesn't become a breakout success, it could certainly be a win if even one group is able to organize on the service in private, without risk of being monitored or having their accounts erroneously shut down.
If you want to check out Mobilizon for yourself, there's a demo instance available to play around with.