It is my opinion only: Outside of overthrowing two corrupt governments there is nothing to be done. No protest will change the result.
That being said, it's still worthwhile and will help build awareness of how this world really works, but it won't get Assange freed.
It would change the public awareness, at least. Force coverage. Start a dialog.
However, my prediction is that there will be no large-scale protest in US about this. All those who are currently LARPing "resistance" against police brutality will just ignore his case. Mark my words.
Please explain how Assange is being treated more unfairly than Breonna Taylor or George Floyd?
Edit: Fixed Typo (treaty/treated)
Nobody cares. If he wanted sympathy from Americans, he should have kept himself out of the last US presidential election. Democrats are going to be hostile to him and Republicans won't care because he's outlived his usefulness to them.
He isn't a journalist, never has been, and it's frankly pathetic that people have decided to retcon the guy into being one. He's a political activist who beclowned himself by aligning with foreign intelligence and they've abandoned him because, again, he isn't useful anymore.