If it's flush on the kitchen counter, it has to be flush on the bathroom counter.
Same material, same lip form, same spacing(on my 2018 anyway).
All that might possibly be required is a piece of 1/2 or1" spacers to get the hinges to space correctly against the bathroom sink cabinet side. Easy stuff right there.
We didn't do that.
While in the middle of the move/change of the shelf the spousal unit wanted a waterproof shelf with a groove around the edge to catch rolling things. We used the hinges from the kitchen sink extension with a Walmart opaque white cutting board as the top/counter. It doesn't match, but it has a groove and is waterproof. We never use the kitchen sink or stove so the extension there was useless. We are putting things like inverter controls, ags controls, battery monitoring on the cabinet wall where the extension was.
When we put the extension on the shower side of the sink cabinet we replaced the wood panel on the shower side with a plastic lens used on trougher ceiling lights. Now we're waterproof there also.
There are(sadly) some sideways pictures in my thread in the link below.