User blog comment:Nightfury4eva/why don't they put game dragons in canon shows/@comment-24413325-20200214143914

In early conversations with the showrunners, they said there would be some Rise of Berk species (but not a Hackatoo, they said very specifically), but it is safe to assume they had to change their plans, likely because of copyright issues, as you said. It would have been thrilling to see a Sliquifier, or Shivertooth, there were so many missed opportunities.

The only most-widely-accepted-as-canon material to include any videogame dragon is the Serpent's Heir. They've got the Submaripper, and the Foreverwing. In Dragonvine they mention the Mudraker.