Doing away with First Past The Post voting in favor of a more representative electoral system (such as but not limited to Ranked Choice voting) will Introduce competition into the electoral process.
This will increase the quality of candidates across the political spectrum. Yes, this would even help the Republicans pick less insane candidates.
We have to think further than the next election. At this point we just have to assume we will win this November and start planning for 2028. There's going to be a big strike that May Day so we would need to have sympathetic representatives wherever we can. As much as we hate biden for solely running on that, "not Republican" will get you far, maybe enough to flip even a local seat
I highly recommend multiple seat districts so that multiple groups get representation. One seat districts are very 1800s.
Regards from Northern Europe.