Repeal of the Chevron doctrine took the power of deference away from executive agencies and replaced it with first-principles judicial interpretation of statutes.
Chevron and the unitary executive theory have essentially nothing to do with each other.
I’m still not sure what point is attempting to be made here.
Well, I believe the opposite. The removal of Chevron was dressed up as more democracy, but in practice, deployed at this moment in time, when Congress defers everything to the Emperor, it looks more like when the Tsar had to decide every little stupid detail. This used up the precious time of the Tsar, in stupid little details (similarities today, reflecting pool, anyone?) to the detriment of the country, and also in the end, the ruling class.
In effect, it did not. All it said is that the powers enumerated to those executive agencies must be more explicitly laid out by congress. But, that’s just not something that’s going to happen.
So, the gap has been filled largely by executive orders.