This is seriously hard to find, even on this website, hadn't it been for the notification I would have totally missed it, it doesn't even appear on the search results. That aside. “Tokyo One Piece Tower: Tongari Shima no Dai Hihou” is a one-time exclusive feature, much like the “Shingeki no Kyoto” with Shingeki no Kyojin, a wide display special featuring a noncanon adventure for the sake of fun. One thing to note, the animation was gorgeous, near the budget of a big budget movie, and the plot isn't all that interesting, just some teasing about Luffy vs. Law, and some Zoro vs. Fujitora and Sanjivs. Sentomaru.
I really don't think it's something that big of a deal, missing on it might leave a huge void if you're a completionist such as myself, however, it doesn't contribute to the “One Piece experience” as you might think.