There's groups like Run for Something that recruit progressives to run for state and local office
A surprising number of potentially winnable seats are never contested. Let's show up anywhere and everywhere to fight back
If you're worried about Republicans messing with elections themselves, you also have the power to help there too by running for state and local offices. Elections - even for federal positions - are run by state and local officals not by the federal government
Realistically, the United States is heading to Balkanization. Probably the single best thing you can do to prepare for that Balkanization is making sure that your city, county, and state elected officials are people who represent you, and that you agree with. You don't want to be stuck on an island in a sea of fascists with elected officials who will sell you out in an instant.