What does platform engineering means for DevOps or sre?

I'd certainly say it has merit - large companies have separate teams maintaining the Kubernetes/Git/CI/AWS/emailing/auth/etc cloud setup that's used by individual product teams, and what else is that if not "platform engineering"? They don't have anything to do with development, we have in-team DevOps guys for that kind of work - configuring the provided K8s for our particular services, making use of the cloud services the platform team has made available to us, writing the Dockerfiles, etc.

If your company is just one product or one team, it might be used as a buzzword. Not when there's tens of products, hundreds of dev teams and thousands of microservices - maintaining this kind of platform is a very distinct discipline from DevOps.

Traditionally, platform engineering refers to a design optimized around creating and maintaining multiple versions of a product with different sets of features (and often different price points).

Note that platform engineering refers to the design priority, not the implementation.

For a dumb example, the implementation of free-profession-enterprise tiers for a web service might reflect platform engineering.

Or the implementation might be totally ad-hoc.

Or somewhere in between.

To explain further, feature flags are a technique that can facilitate platform engineering.

So platform engineering is a real and established thing.

But that doesn't preclude it being used as a buzzword by someone who doesn't know what it is.

Good luck.

Sounds like buzz word to me. I take it to mean “we have these micro services/applications, go setup dev, qa, prod, etc. environments for us.”