What role should DevOps play in a software development team?

What role should DevOps play in a software development team?

A little backstory.

I work for a medium-size company. We have several teams of about 10 engineers each, all work in the cloud space and also in the application development space, designing web applications and other services that get hosted in the Cloud, such as AWS Lambda or AWS Elastic Beanstalk, with supporting services (KMS, Secrets manager, EC2, SNS/Pub-Sub, etc.)

We also have a DevOps team with the following roles:

1. Appropriates cloud entities needed by the cloud development team into a Terraform script and hosting that in the cloud and propagating it to all environments, including production
2. All billing (cloud developers don't know anything about billing)
3. All production deployments
4. Handling of all KMS key creation etc. via the Terraform script
5. Handling of cloud user permissions for all cloud developers

I've often thought our DevOps team has way too much power. To make matters worse, this "team" consists of only one person! I've often been concerned that if this person left the company, us cloud developers would be scrambling to figure out what our DevOps engineer does and when. My manager came to me asking me how to best mitigate this situation so I'm leaving the door open:

How should DevOps fit in a software development team? How can our situation be mitigated?