The thing that stands out for me here is the support for PostgreSQL extensions, which is pretty thin in other hosted PostgreSQL offerings.
We couldn't agree more, extensions are fascinating area for Postgres, with several hundred that already exist they remove a need at times for whole new databases to crop up. The fact that you can build on a Postgres foundation as a solid and stable database, but add new functionality without waiting for a new major release is great.
Any good site where you can easily search and/or explore these hundreds of postgres extensions?
Please bring this to GCP!
GCP is definitely on a our list to explore, we don't have a firm timeline for it yet, but anyone that is interested in GCP we welcome hearing from to help gauge interest.