There are five 2B items in the Itaku gallery: 3 static pictures, 2 animated PNGs. If you see those five items, you have seen everything in the gallery. If you're unable to see them, then I don't know what you're doing wrong because they're viewable with a normal account with NSFW enabled.
In fact, I just tested viewing the 2B pictures in a browser where I'm not even logged into Itaku, and once I enable the NSFW / Questionable tag, I can see the five 2B pieces. So you don't even need an account to see them.
Unless iPhone is blocking NSFW content, then I have no idea why you're unable to see content that is viewable even without an account. You must not be clicking the options I mentioned up above.