Well, I ordered one out of curiosity, and it arrived an hour ago. I ordered blue, to increase visibility. Elago sent me black instead (the packing slip indicates blue, the box indicates black). Someone on the marketing team made a box with a hole in the back, labeled, "The color of this product", then someone else on the marketing team elected to put the case in a white plastic wrapper, inside the box, rendering the hole useless. Not exactly off to a good start

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The case is well made, out of a very solid block of silicone (I've seen cheap cases that have hollow spaces inside to save on material, which end up feeling flimsy). This solid construction makes it surprisingly heavy, compared to the remote itself, more than I would have guessed. The substantial silicone wrapping also means your AirTag is very well protected: nothing can hurt it - and not much high-frequency sound can get out from where it's ensconced inside. So don't expect to be able to locate your remote by the AirTag's little chirps. Elago makes some nice accessories, but I didn't find this case of theirs' to be an improvement on the no-name silicone case case I got from Amazon a month ago (which is more of a close-fitting silicone skin, follows the contours of the remote, makes it agreeably grippy, has a light blue color that's easy to spot, and was half the price). I reverted to the old case after about twenty minutes.
Why is the back curved? That means the remote will not lie flat on the table.
Because it's got an AirTag in the middle of the back. If it weren't curved, the whole case would have to be close to an inch thick, and even heavier than it is.
(I expect that Apple didn't build in an AirTag equivalent because the design for the new Apple TV has been sitting on a shelf for a long time, possibly before the AirTag was finalized. I do wish, though, that they had built in a tiny speaker or beeper, behind one of their arrays of pinholes, so that they could eventually have the Apple TV be able to send a command to the remote to have it play a noticeable noise. I get that being able to locate things with an arrow on your screen is even cooler, but requires the Apple TV owner to have one of the latest iPhones as well.)