I know the isn't officially canon but personally from my experience with the game, I feel like story-wise, the game was made to be canon as it does nod and reference towards things that do exist in the Zelda canon, not the three worlds through time of SS, OoT, and TP but elements that exist in the main game's world because of those games, like Demise's cursed cycle, the Gerudo desert from TP, a form of the Faron Woods that bears resemblances to the Faron Woods from SS, the Faron Woods from TP, the Lost Woods, and the Kokiri Forest from OoT. The is the Eldin Caves which bears elements from the Eldin Volcano from SS and the Dodongo's Cavern from OoT. And lastly, the Temple of the Sacred Sword is similar to the Temple of Time from OoT and the one from TP and Hyrule Castle is like an improved version of the one in TP in a way.
Also, the game does prove some of my theories I've had since 2011 to be true for a game that is unfortunately, not officially canon. If the game were to be counted in the timeline, I, personally would place the game after TP, reasons being, one, the game definitely would not be before OoT since it refers to OoT's era as something that is past, two, the way Ganon has evolved since OoT, Ganon started off much thinner and more human like in OoT, in TP, he more bulky and demonic, in HW, he's much more bigger, more bulky, more demonic, and closer to his returning to his true form as Demise, not to mention, he has the same head piece he wore TP, only upgraded to suit a more powerful improved look, and finally number three, just the everything is set up, Temple of the Sacred Sword serving as like the new Temple of Time at the time, Faron Woods is no longer south but instead, it's north of Hyrule Castle, Gerudo Desert is the same as in TP, and lastly, Hyrule Castle still remains in the center.
Anyways, this is just my theory and opinions.