I imagine just scanning the QR code will be enough regardless of location. So just go into any GameStop, scan the code, and leave. Which is still a little awkward to see people do by itself haha. Or in your case, scan the code from your photo album when you're home, I really don't think it'd restrict you if you're not in the store since it's probably not coded to actually check your location when you do these things. As long as you scan the code itself, you should be fine.
I wish they wouldn't do this during a pandemic, especially with all the bad rep GameStop is getting. We need to catch up with the times and be given them out via WiFi. I'll probably just breed my own.
Yeah, I don't really mind because it's not like it's one of those mythic events where you can't get the Pokemon otherwise, if you don't want to do it then just don't. Like you said, breeding is always an option and getting the Shiny Charm is so easy, anyone breeding for shinies should have it anyway.
I am probably going to do it but odds are, I'll end up forgetting anyway since Toxtricity isn't a Mon I really care about.