There's some indications that Google would support Postgres as part of the CLoudSQL in the future. But there are already multiple DB-as-a-Service offerings that

There's some indications that Google would support Postgres as part of the CLoudSQL in the future. But there are already multiple DB-as-a-Service offerings that provide PostgreSQL in Google Cloud. My company, Aiven (https://aiven.io https://aiven.io) is one of the providers and I believe Compose, DatabaseLabs and ElephantSQL also provide managed PG in Google Cloud.