The article says that this proves that Einstein's equivalence principle (resulting in relativity) holds in this test of a falling quantum particle (where gravity results in a phase shift in the quantum state).

It doesn't show/prove how general relativity and quantum mechanics interact.

NOTE: The Dirac equation and Quantum Electro Dynamics (QED) unify quantum mechanics and special relativity (non-accelerating frames of reference).

So the remaining piece is either to extend QED/QCD to accelerating frames of reference or to quantize general relativity. That would likely predict the phase shift observed in this experiment.

From the article: "The result does not unite quantum mechanics and gravity, nor does it show that gravity itself is quantum".

I must say, it's actually quite refreshing to read an article about a science topic that conveys the caveats and limitations of the study. Far too many of these studies get filtered through the news outlet hype-machine

I'm way in over my depth here, but does this maybe that the unification of gravity and quantum physics is further out of reach than we might have hoped? Because it would be easier if gravity disappeared at quantum scales - then it could be understood as an emergent property that emerges out of quantum when you move to bigger scales. But now we have to find something that underlies both.

I have, but no one takes it seriously. But who cares, one needs to answer ones own questions, and not of the entire world.