Someone was asking recently about the accessory that goes over one of the rear side windows to allow you to pass a power cord from inside the vehicle while keeping the car secure. I searched for the thread, but couldn't find it for the life of me. Hopefully whoever was asking the question finds this thread. The part number is: 67217-47020 - STOPPER, REAR DOOR GLASS Sorry to say that it appears to be a Japan-only accessory. If you really want one, your best bet is through a Japanese importer like the people who found window visors.
I found that there are other similar products like this Window pass through for Starlink cord – Savage UTV I haven't tried it though. It might require dismantling and resembling the plug to let it pass through the tiny hole.
Ah, but that wouldn't have the cute little Prius icon and the "HYBRID REBORN" and the "POWER SUPPLY" tag to match all the other silly tags on the car.... (I just got my official stopper today, along with the jack - made me laugh that to see even more of that...) Link from the documentation that came with it took me to this site with a nice little animation of the powered-by-a-Prius lifestyle... トヨタ トヨタの給電 | トヨタ自動車WEBサイト
I have a NOCO battery minder permanently installed and I run the power cord out the lower part of the rear hatch. I close and secure the hatch. No effect on the rubber gasket thus far.
Is that kinda thing big enough for a power cord though? Yeah but, it also has a special spot under the rear floor in the trunk that it slots into perfectly! I'd love something like this in the event its raining outside so I don't have to have it in the garage with the window and garage door wide open
Some images make it look very big. But if you see the 3rd picture, you'll see that it's not so so huge.
Weird that no one just removes the little black rubber drain plug at the bottom of the trunk flooring and runs a wire out that way. It's secure, you don't have to import any parts, it doesn't mess with weather seals.
But you'd have to dismantle loads of stuff to get there and you couldn't actually pass the plug through it. Not very practical. Maybe if you weren't planning to drive the car, and just use it as a permanent generator?