Yes Spyro could appear in it but he couldn't be purple and gold cause in this universe of Dragons this is not connected to The Legend Of Spyro. Reason why is cause this focuses on the Last dragon of peace (Dark Gray and Gold) known as Wedger.
The plot is very dark. With All the Dragons of Peace gone the Kingdom of Light is forever changed into a Kingdom Of Darkness.
However one egg infused with a spirit of an ancestor of a dragon of peace changes the young hatchling's life forever. Now destiny has called him to help the Rebellion. Re-unite the four races of Men, Dwarves, Elves and Dragon. And bring back light to the kingdom.
The ruler of the Kingdom is known as Dranus who is a corrupted part human/dragon and very very dangerous to cross and anger.
Wedger is the only Dragon Of Peace left for now. But a very strong group of warriors known as the "Guardians Of Light" are very powerful like the Dragon Of Peace. (You)