Would you consider TESO canon?

There is no question about it. Eso is canon.

 

It takes pace before Morrowind and Skyrim which gave them the opportunity to get the lore right. It is called creative freedom.

 

There are references of all the gods including dragon born. It actually establishes itself in the timeline pretty well.

 

Anything not licensed by Bethseda is not canon no matter what anyone says. Other than that, Eso the game is definitely canon.

 

ESO came to bridge all previous versions. Of course there were some inconsistencies existing pre Eso, but they were fixed by changing some lore.

 

I'm pretty sure if you point out something that doesn't make sense in the lore, there will be an explanation.