Sustained, Committed and Preemptible
vCPU and memory usage for each of these categories can receive discounts VM vCPU and memory usage for each of these categories can receive discounts Sustained-use discounts-Google offers up to 30% off for workloads that run for most of the billing month on GCP services.
Committed-use discounts-users can save up to 57% by committing to use an instance for a certain time period, with no upfront payment and with the flexibility to change instances during the commitment period.
Preemptible VMs-similar to the concept of AWS spot instances, Google offers up to 79% off for Virtual Machines that may be shut down at any time and replaced by others.
Reference link- https://cloud.google.com/compute/docs/sustained-use-discounts Reference link- https://cloud.google.com/compute/docs/instances/signing-up-committed-use-discounts Reference link- https://cloud.google.com/compute/docs/instances/preemptible

Reference:

The Bare Metal solution is the recommended approach. You can deploy Oracle capabilities like clustered databases, replication, and all performance features at licensing costs that are similar to on-premise systems

https://cloud.google.com/architecture/migrating-bare-metal-workloads

Billing contacts

Firebase Cloud Messaging:
Firebase Cloud Messaging (FCM) is a cross-platform messaging solution that lets you reliably send messages at no cost.
Using FCM, you can notify a client app that new email or other data is available to sync. You can send notification messages to drive user re-engagement and retention. For use cases such as instant messaging, a message can transfer a payload of up to 4000 bytes to a client app.
Key capabilities of Firebase Cloud Messaging:
Send notification messages or data messages: Send notification messages that are displayed to your user. Or send data messages and determine completely what happens in your application code.
Versatile message targeting: Distribute messages to your client app in any of 3 ways-to single devices, to groups of devices, or to devices subscribed to topics.
Send messages from client apps: Send acknowledgments, chats, and other messages from devices back to your server over FCM's reliable and battery-efficient connection channel.