I'm kinda with your son. It's going to be covered with brake dust and other road crud exactly the same as what's on the wheel!
Yeah, what are you thinking @Mendel Leisk?! Hopefully, at least those brake pads are asbestos-free. LOL
So, @Hammersmith, it looks like I have solved the mystery. 90942-05039 and 90942-A5002 are entirely identical and both made in Japan by Pacific Industrial Co., Ltd. The difference is that Toyota buys them from Pacific Industrial Co., Ltd. in bulk, and 90942-05039 is packaged in bags of ten in Japan by Toyota Japan, whereas the 90942-A5002 is packaged in bags of ten in the USA by Toyota USA. What lengths we go to keep our Priuses stock. LOL We have learned something new about the Toyota part-numbering system though. Apparently, an identical part can have multiple part numbers depending on where it is packaged, especially if it is a bulk part. https://partsouq.com/en/search/all?q=90942A5002
Good to know. I'm planning on buying 20 or so during Black Friday because I swapped to winter tires this weekend and noticed(because of this part of the thread) that my caps are a mishmash of different types after only 2.5 years. I'm going to buy a bunch of Toyota caps and make sure everything I own that use valves uses them. Lawn mower, snow blower, wheeled carts, etc. Plus have a bunch more for spares.
Note that for non-TMPS tire valves, there is the CL type tire valve cap from Pacific Industries Co., Ltd. instead of the PVC25 type. I don't know if Toyota still uses it and there is a Toyota part number for it. My 1985 Corolla had that tire valve cap on the spare tire. It has a rubber bushing as well but much fewer threads, and there is no protruding concentric cylinder with a lip inside.