OP is talking about photonic bandgap fiber I think, or perhaps another kind of photonic-crystal fiber. At any rate, whereas in regular fiber guiding light via differences in refractive index the speed of light is only about 70% c, photonic bandgap fiber can reach something like 99.7% c, which is close enough to c in vacuum as to essentially eliminate the difference vs a free space EM link (particularly for space-based ones which face an extra minimum RTT distance penalty). Last I checked though 3-4 years ago they needed fairly frequent repeaters, were harder to mass produce, etc.

I don't know of any being deployed long distance, though in principle they'd be really valuable for intercontinental backbones. Starlink fills a huge gap in existing infra, and there are places that won't see any sort of fiber, let alone fancy microstructured fiber, for the foreseeable future (or ever, obviously in the case of ships/aircraft). But the bandwidth isn't great. Each current sat does I think 20 Gbps, and though no doubt that'll increase over time that's literally orders of magnitude from this single cable alone. Having the sats support direct ground optical links for backbone usage might be interesting someday, but weather attenuation will never stop being a problem with that. Starlink is filling in the gaps for fiber infrastructure, not replacing it. They're complementary.

So I agree it would be great to see more advanced fiber deployed long distances and start to shrink latency for everyone, and interesting to know what technical obstacles remain if any (maybe a lot remain?). A 40% speed boost while still having massive bandwidth isn't nothing.