Two party state baby

Not that have a snowballs chance in hell of winning

There are some socialists elected to regional positions, like city councils, school boards, etc. The most prominent is probably Seattle councilwoman Kshama Sawant

You'll need an insurgency for that

Nope. Alternate power structures that can seize power during crises is how socialist revolution can come about. Much writing on this, here is a link I randomly googled:

https://dsa-lsc.org/2018/12/31/dual-power-a-strategy-to-build-socialism-in-our-time/

Bernie was the only one with balls to step forward. If there are any others out there then they're hiding or being hidden somehow because we don't see them.

AOC is as close as you'll get and the right immediately "Hillaried" her so now she's "damaged goods." They're very good at muddying waters and ruining candidates via propaganda and brainwashing society.