Google Cloud Certified Professional Cloud Developer exam is designed to test the technical skills related to the job role. Hands-on experience is highly recommended for the exam. Here is the list of important topics to focus on while preparing for the GCP Professional Cloud Developer certification exam:

Identity-Aware Proxy
Endpoints
IAM
Stackdriver
BigQuery
DataStore
App Engine
MemCache
Cloud SQL Proxy
Kubernetes Engine
Managed Instance Groups
Deployment Manager
GDPR
Cloud Armor vs Cloud Security Scanner
DNS
Cloud Storage
Cloud Composer
Cloud Spanner
Cloud SQL
Cloud CDN
NAT
CloudBuild
PubSub
Cloud Tasks
Key Management Service