Apparently if you want one you need to search for “air conditioner fin comb”. I did that and ended up ordering “Air Conditioning Fin Comb Condenser Clean Refrigeration Tool (Plastic Comb)” from eBay, after first checking for local options.
Edit: I just looked up where this had got too. Apparently it was posted in Guangdong on 11/04/2024 and has now left China. Delivery is estimated to be before 25/04/2024. I’m not concerned about the timing, so long as it’s used before the next heating season, but I am concerned about its carbon footprint.