as stated many, many, many, many, many, times, please read, there wont be a gallery mode, it does not have that type of artwork
Sadly it's hard to read 1000+ pages of stuff. and also adding a gallery mode or semi gallery mode is hard but not impossible.
Just for starters make each scene (pub minigame, stripping minigame, battle loss on floor 1, etc) its own NPC with all of them in one room. Add another NPC that can set your health, enemy health, enemie waves and time to be infinite or massively increased. Then when in the actual battle/minigame add an ability to instantly win the fight or reduce the remaining time by a large amount. This immediately fixes needing to to sit around waiting for enemies to finish even after you use the SewerSlide buttons and can jump straight to loss scenes by talking to the NPC or not have to worry about time in the minigames. Even without adding infinite health or time just being able to select something like the ending scene in the wedding dress as its own battle is probably something that could be added pretty easily since it would effectively just be triggering the battle through an NPC.
Of course this doesn't make it easier to see specific actions within the minigames or battles but using the same thing from the endless mode post game you could pick and choose what enemies how up and how many rather than luck. This also means not being stuck in loops of needing to sneak past enemies and failing to then be forced into another scene after defeat. I have no idea how the artwork would prevent a gallery mode outside of the dev simply not wanting to add it.