[Nevermark]

Replying to you again, very late.

> Fortunately we can look to other countries that have managed to avoid political duopoly by using voting systems which don't penalize people for voting for new parties. Even better, some US states have already implemented such a system[0], and, going back to your point about constitutions, the people of Maine managed to introduce RCV not because of a constitutional requirement, but despite a narrow (state) constitutional prohibition.[1]

I think you are right, voting systems are the best place to start.

That and prohibitions on justices and congressfolk from weighing in on matters they have a personal or political interest in, such as receiving political funds or assistance.

Imagine if donating to a politician whose influence you want will make it more likely they cannot help you. That leaves donations reflecting people's assessment of who will better run the country in a more general sense. Those donations look more like "free speech" than the rampant influence purchasing that overwhelms the system today.