The Green party gets more attention in left-leaning circles because there are people sympathetic to it and there are people who want to blame them for the Democrats losing. It’s not because they’re actually more popular than the Libertarian party, which regularly gets like 3 times as many votes.

2020: 1,865,917 (LP); 405,034 (GP) 2016: 4,489,359; 1,457,216 2012: 1,275,923; 469,627 2008: 523,713; 161,797 2004: 397,265; 119,859

So it’s completely wrong to say that “there aren’t any right-wing third parties making any kind of a meaningful run.” It’s just that your perception of how popular the Libertarian party is compared to the Greens is distorted.