Missing Pokémon GO Loading Screens

[TeridaxXD001]

Right now, there's only three of these on the site. I'm trying to find the rest (in their in-game 1024x1024 resolution), and I've found several on a few Github repositories, but three still elude me: New Years 2016/2017 (Generation II babies watching fireworks), Spring 2017 (Steelix attacking the player) and Halloween 2017 ("scary" Pokémon standing in front of a full moon in a pumpkin patch).

Now, I was able to find a file, apparently for the New Years 2016/2017 screen, in a version 0.53.1 APK called "WarningScreen_BackgroundPlate_NewYears.png_enc." It's a text file rather than an image file, but it's 3.72 MB in size. It appears to be a PNG that's encrypted. I've uploaded this file here.

Any ideas on how I can decrypt it? The Pokémon GO page on The Spriter's Resource is in desperate need of updating, and this is as good a start as any.

[TeridaxXD001]

I'm coming back to this old thread. This is the only other person on the Internet that has called attention to the:
https://www.reddit.com/r/TheSilphRoad/co...g_encoded/
Niantic did it again for the 2019 New Year's loading screen. The thread digs a little more into it, but they're still ultimately unsuccessful in decoding it.

[TeridaxXD001]

...and apparently there's yet another: "haloween2017_18.png_encoded.txt" (Halloween is misspelled in the filename). I'd really like to update the sheet with these.