The real solution is to force these kingdoms to build permanently open gates and roadways that connect the land, increase all around traffic and opportunity.
Only when people turn from digital vassals to digital citizens will we emerge from the middle ages we are currently in. In this sense the most important development in the online world is still ahead if us.
Don't get me wrong, it is admirable what a handful of highly motivated people have achieved with activitypub, atproto etc. (to mention just some currently trending designs). But what needs to be done to deprecate the pattern of digital feudalism is a much bigger challenge.
The main way to move forward will be to incentivize (through legislation) many more actors (not just social media reformers) to invest and experiment in this direction, away from the feudal hypersurface that is crushing our horizon. Its the only way to explore the vast number of technical possibilities and economic patterns without being hampered by biases and blind spots.
We don't know what a digital democratic economy and society exactly looks like. Its not been done before. Maybe more than one patterns are equally viable and it becomes a matter of choice and/or random historical accidents.
But we do know that we are far from anything remotely compatible with our purported norms and values.