It is similar to open source social media. No single entity is in control. No single company or government that can use that power to control the users. For the end user the result is that bitcoin is more like paper cash than other digital money. You and only you are in control. It is extremely hard to stop you from sending or receiving money.
Just like with the fediverse, there is no Elon Musk or Mark Zuckerberg to kick you out. With bitcoin there will be no Putin or Trump to freeze your bank account.
100% that being open source is not enough. Just like the fediverse the protocol is really important.
But if the fediverse protocol and all servers and clients are proprietary we would be in a bad place.
The bitcoin protocol makes it possible for everyone to run a bitcoin core node very similar to that anyone can run a fediverse server.
Btw, that signal is actively working against federation makes me so incredibly disappointed…