This has been delayed by logistical issues and various COVID infections so the site is somewhat half-baked right now, but the slate is done and you can donate so if you want you can just go ahead and do that right now: https://superswingdistricts.org
Of course the problem is that there are a zillion downballot candidates and it's hard to know which ones are really high-leverage without doing a bunch of math. My uncle, Dr. Joel Lefkowitz, a professor of political science, has done that math to find those downballot races whose voter mobilization efforts will have maximum impacts up and down the ballot.
I will be working on adding a bunch of additional information to the site over the next day or so, and when I've done that I'd love it if somebody could put me in touch with the folks who were doing the "Mastodon for Harris" campaigning earlier, to see if we can have the fediverse punch above its weight here
I will be posting more about it as I fill out candidate bios and more information if you're interested, but the high-level pitch here is that (as you know) gerrymandering and the electoral college fuck up the democratic process, making certain elections matter more than others, and (also as you probably know) high-profile federal candidates raise a LOT more money, and can use it less effectively than downballot races which are often more consequential but starved for resources