The closest we ever got was Ross Perot, who ran a huge third-party campaign and seemed to be talking sense at the time. He even had long-running infomercials about how he planned to set the Reagan-Bush economy back on track.

You can look up the elections of 1992 and 1996 and see how that worked out.

The problem now is that a Republican president along with a Republican congress would likely be able to neuter federal elections entirely, so that you would only get Republicans in federal office. Period. If they're feeling extra fashy they might imprison (and execute) Democratic politicians, and then criminalize left wing rhetoric the way they're trying to criminalize drag queens. Note that George W. Bush had an both the House and Senate on his side when he came into office, hence he went far-right distressingly fast, considering his compassionate conservative campaign image.

So your vote to slow down the rise of the white Christian nationalist movement and the authoritarian takeover (led currently by SCOTUS) is more important than trying to get a third party candidate into office. Especially since your third party guy even if he's a Jimmy Carter x 11 principled statesperson is not going to be able to get much done without cooperation from the other parties to get laws passed. And they are still beholden to corporate interests. So getting a single third party dude into office is still only a tiny step forward.

The US system is (and always was) as fucked as this sounds. Look up Professor Larry Lessig and his TED talks in which he discusses the degree of corruption of the federal government. Sadly, all the long term solutions are likely to be outpaced by the climate crisis unless the public finds a way to threaten the power and legitimacy of our officials.