I know you're joking (and it was funny), but thinking about it I think it's actually harder in some ways because you go from almost no traffic most of the year to needing to scale really, really fast. And the PWA has a ton of games and other things in it, so not as simple as the old school trackers that don't even need a backend cause all of the "tracking" happens in the browser

I'm 100% unawares of the Santa Tracker app that you speak, so yes, I was attempting to be funny. However, for that 1 day of the year, is it that hard to have the "tracking" done locally since it's literally just made up data? Just know the localized time and where sunset is, and have the "Santa" moving around in the nighttime areas of the globe. Guessing on efficiency suggests to me rapid movements along the North/South with magical speed roughly equidistant from the terminator at a distance equivalent to midnight.?? Again, since it's 100% make believe, it's not like your browser has to show the exact same location as someone else's.

Any other games the app might be included are out side of the scope of the imaginary app in my mind.