It's a common assumption made due to the relations between god and Veldanava in the LN, many assume they are the same in the WN as well, but that is not true.
Let's get some facts straight.
True dragons are also known as "Holy Spirits."
Great Spirits are the foundation of the world, the so-called 8 pillars of the Great Holy Spirit
Using this translation for now
The Great Holy Spirit is the God.
The main misconception here is that "holy Spirit" refers to Veldanava or the great Holy Spirit, but in truth, it just means True Dragons.
So yes, Veldanava is a True Dragon, He is a Holy Spirit, but not the Great Holy spirit. He also helped shaped the world due to his participation of creating beings
Also, in the WN, It's Ramiri's that's God's avatar or apostle or whatever you wanna call it.