Latest update has a picture book gallery function apparently. I am procuring it from eyny. If there is interest I can make a MEGA link. There is no loli or shota content AFAIK (if there is REPLY IMMEDIATELY) so it should be safe to share.
C:\Users\Username\AppData\Local\name of your game folder\save
Final edit: I have game. Posted txt file. Cyptic in the usual manner. Also I can confirm that gallery area in 4th door (the paper one) has all bosses except for the final bosses (sadly I have already beaten them so if someone wants to do the game all over again and post saves there go ahead). The gallery is also no longer bugged (i.e hitting two enemies at once is now much more difficult so H-scenes no longer bug out now) but I did not check if you can open, exit and then return without issue (but I assume that's fixed and that's a safe assumption with how different the gallery is now).
As a final note: I believe the game only has two endings but given the sadly dark nature of the story, the second end seems the most optimistic.