So, what would you consider canon?

With Exedra releasing in a few days and being set as being an adaptation of other stories from throughout the series, I'm curious on what the general consensus of what's 'canon' is.

My general understanding of the series is that the Original Series/the movie adaptations and Rebellion (as well as Walpurgisnacht Rising when it releases) are the 'absolute' canon. Aside from that, it seems reasonable to say that the Wraith Arc, the Different Story and the Drama CDs are all canon as well, while the Magia Record anime in specific is non-canon, but what about everything else?

I feel like I generally see people consider the Magia Record game non-canon, but still consider Scene0 in specific canon. But what about some of the other stories from Magia Record? I often hear people cite Nagisa's backstory from Magia Record as canon, so would the consensus be that those stories are canon (when the relevant character canonically exists)?

But also, taking a step back, is there any real reason the Magia Record game isn't considered canon? I haven't played the game, but I've heard that it takes place within a pocket dimension that 'leeches' off of Ultimate Madoka, to allow for the indefinite existence of witches, without any character succumbing to their despair.Is there any real reason Magia Record isn't canon? And if Magia Record IS canon, does Scene0 occur exclusively within the universe of Magia Record, or is it also true to the universe of the main series?

What about the numerous other spin-offs? Joan of Arc appears in the Original Series, which arguably would imply Tart Magica is canon, but also, they appears alongside several other real world figures and it's possible for a character from a Spin-Off to exist without the Spin-Off being canon.