In the end HexOS turned into more of a TrueNAS installer for me. I don't know if that saved me a ton of time and hassle, or if it was more like an hour worth of following a guide instead, but either way getting up and running was very painless.
After that, I can't think of a thing HexOS has actually fully supported without needing to pop into TrueNAS. Not even the health status in HexOS can be trusted, which is stil baffling to me. I've been saying I feel it was launched very prematurely, and I maintain that. I'm hoping that it was because they desperately needed cashflow, in which case HexOS could turn out well in the end. If, on the other hand, they felt it was in good shape to launch to early adopters, I would be much less optimistic. Time will tell.
I've gotten the NAS to a state where it does the job now, without having done anything to break or confuse HexOS (at least that I can see), so I'm just using it now and seeing what the future brings. It might be HexOS, it might be shedding HexOS and just going pure TrueNAS.
In a sense you could say I've shelved HexOS, because there's no reason for me to ever access its interface. If my boot drive exploded today I would probably just install TrueNAS and recover the pool there instead, because HexOS doesn't even offer a way to backup and restore itself (another baffling "nah, we don't need that before releasing" decision), or even recover an existing pool without at least threatening to wipe it in the process. But, technically, HexOS is still on my server, so there's that.