It's the same code. The only thing it doesn't include is the global scheduling and orchestration, but you don't actually want that locally. (And honestly... that stuff is a bit of a beast.)

Durable Objects are fully supported by workerd (and Cloudflare OS uses them extensively).

There is, however, one catch currently: Durable Objects don't scale out well without the global scheduling. For running Cloudflare OS for one user, this is actually no big deal, but a company-wide instance might not work well.

But I'm actually fixing that:

https://github.com/cloudflare/workerd/pull/6780

Unfortunately didn't get enough time to land it before this release, but it'll come soon.

With that I would expect a self-hosted Cloudflare OS on your own cluster to work quite well.