There seems to be some progress lately on Haiku. Brian Lunduke talked about it a bit here:
https://www.youtube.com/watch?v=i-tm7lxHDyE
I remember taking a look at it some years ago, but the alpha releases seemed to be creeping along ever so slowly. It's now in beta.
Highlights: Single user os; multimedia centric; responsive performance.
The sound system is OSS.
It might end up making for a nice os for daw purposes.