For those looking for official accessories, certainly do try going into your local Game store, I've managed to buy the media remote from the MK store and I believe they had few others left available while their website is out of stock.
I've not seen the media remote out of stock anywhere to be fair. I'm a bit confused as to the point of it, most people have smart tv's and can control the PS5 with that remote.
edit: Just had a look, apparently it is, odd.