Google's reach could be a huge advantage. But there is a difference between having a platform and getting people to discover and play the games. This is a question, not a claim that Google will promote every creation.
Full breakdown: https://youtu.be/ESr-JxuIQg8 (also linked as this Short's related video)
Unity Spark: https://unity.com/spark
Google Playground: https://playground.google.com
Roblox Assistant: https://create.roblox.com/docs/ai/accelerated-workflows
This is an announcement discussion, not a hands-on review. Spark beta availability and features can change.