If you're running Linux as a matter of technical preference and not as a philosophical opposition to commercial software, I've had really good luck with just installing Office in Crossover.
Can't Libre office deal with pptx by now?
It always could 'deal with it', the issue is getting it to render identically to PowerPoint, which is virtually impossible to accomplish for non-trivial presentations, it seems. Likewise for other Office files. iWork has the same problem.
But surely Google docs presentations are fairly non-repeatable across browsers, operating systems, and years.
All "modern" browsers render Docs well. Not sure what difference the OS makes, after all, it's just a vessel for the browser's rendering engine.
Font rendering can differ between different OSes but it's usually not too bad.