I think moving to a 3-2-1 voting system instead of FPTP, IRV or Proportional would resolve most of the polarization issues in a few cycles. I think it's the easiest way to force deliberation and moderation at the single district/office level without conceding local representation or complexity for the voter. The key is not having a one dimensional optimal strategies or suboptimal equilibrium that result in plurality rule or tyranny of the majority.

I'd modify it to allow a super yes/no with double the value per voter to force people to be a bit more selective.

https://electowiki.org/wiki/3-2-1_voting