I think anything that runs on ARM devices and on Linux would theorically do it. So Shairport might be the thing (audio only afaik). But I'm not experienced with building software for the Steam Link though. But if you wanted to be guided, here it is!

there might be something in kodi for that

Tried building it, but I don't think the Steamlink has all the pulse libraries required. I tried the updated Shariport-sync as well, but that has many more requirements. Made an effort, but it would take someone more familiar with it than me.

I second the idea with Shairport, it is a very good software, I've used it on my Linux NAS.