Now, after the dust has settled, what the hell was it?

Theories:
>Hydrogen iceberg
Pros:
Could explain the strange acceleration
Possible theories on how these theoretical objects could be formed
Cons:
Such object has never been observed before
Some models predict these things would evaporate upon close encounters with stars

>Comet with undetectable comma
Pros: Explains the acceleration
Comets should be one of the most common interstellar objects
Cons: Some models predict an outgassing should shatter or deviate the trajectory of 'Oumuamua yet that wasn't observed
Weird shape for a comet
Weird tumbling motion

>Asteroid
Pros:
The most common objects
Cons:
Doesn't explain the odd brightness nor the acceleration

>Planetary fragment
Pros:
Explains the weird shape
Planetary collission could explain the tumbling
Cons:
Doesn't explain the weird reflectivity
Doesn't explain the acceleration

>Ayyyy object
Pros:
Could explain the strange shape
Could explain the acceleration
Could explain the very high reflectivity
Cons:
Doesn't explain why it took 'Oumuamua millions of years of wandering around to get here
Doesn't explain why it's trajectory and speed matches the Local Standard of Rest, which is more consistent with a natural object that has been wandering the Galaxy for millions of years