A semi related but enlightening (thought) experiment.
There is a theory that our universe isn’t actually 3D is actually a projection/simulation on the 2D surface of a black hole (aka the big bang). If this were the case, then the practical differences would be almost nonexistent. The exception is the planck length. This is the smallest length that is meaningful. If our universe is 3D, we are extremely far from being able to measure effects anywhere close to the planck length. If it is 2D however, that length appears FAR bigger. It wouldn’t be that far below what our current gravity wave detectors can see.
The effects of this would be similar to a simulation running near its limit. It would be the equivalent to floating point rounding errors.