Load / Stream 3rd Party Scene?

Hello, I have a requirement to load scenes that won’t exist at build time. Our customer would like game developers to be able to add to parts of his game as it grows. The current idea is to make it so 3rd parties can build scenes for uploading to his servers and then load them into the game when certain easter eggs are triggered.

Is this possible?

The various scene streaming options seem to be tailored to optimization of scenes that exist at build time. Does anyone have an example that streams or loads scenes from an external unity project?

Thanks in advance!

Yes, using Asset bundles.