Making a new post, regarding how to get the serial code.
Indeed, the event IS location locked. Here's what I did to get it to work on my PC (probably easier if you have a suitable android phone) Mod reminder: In this instance, we will not give links to any of the apk or programs mentioned below, so don't ask.
1. Open up Bluestacks 4 (install it if you don't have it)
2. Install Developer Options apk
3. Install Pokémon Pass 1.0.2 apk
4. Open Developer Options, Access Developer Options, set Select Mock Location app to Location Provider
5. Open Pokémon Pass, choose location, and Location Provider will pop-up.
6. For me, I set GPS Location to 60 W E Dekalb Pike, King of Prussia (big Target store).
You may need to take a few steps after setting location, for the GPS to recognize that you're there.
[While I didn't show it in the image below, pasting the address ^ to Search will help.] 7. Go back to Pokémon Pass, sign into your PTC account, it'll redirect you to accept Pokémon Pass T&C, accept it.
8. Now restart the Pokémon Pass app.
9. Now press the Start on the You have arrived window that corresponds to the shiny giveaway.
10. When it asks you to scan the QR code, just click on the (?) button on screen, then proceed to Skip this Step
[only works if the store didn't get a QR code]
If you're unable to skip it, scan this code: 11. At this point, all that is left is to Get Download Code. You'll be given 3 codes per PTC account logged in usage.
If you missed the code, you can go back to Completed Activities on the first page, and see it from there.
If the code is too small/not readable, you may want to go to Bluestack's settings (not the settings accessed from apps) and change Display Resolution to Custom Size: 1024 x 576
Some images:
edit: Useful information that I've verified, however use at your own risk! (maybe the server logs which PTC account did multiple redemptions?):