I'll re-recommend KSR's Mars trilogy. It's not a high-concept space opera so you don't have borderline-fantasy elements popping up. It not apolitical, but nothing is.

You might like Arkady Martine's Teixcalaan series.

You might like Ada Palmer's Terra Ignota series.

They're both history PhDs, which gives them a better perspective on some things, but I don't think it helps the plausibility of their scifi.

Is Dune too close to fantasy with a veneer of spaceships?

If you're vehemently political, whether libertarian or progressive, even if it's just on some issues, that severely limits what scifi you'll be able to tolerate.