Maybe time to answer this ? It is now technically possible.
From Roon release notes:
Roon API (BETA)
The Roon API will allow developers to enable:
Custom volume controls even if the device is not Roon Ready
Custom convenience switching/standby can be used even for devices is not Roon Ready
Display of now-playing data and transport controls
Lightweight hierarchical browsing
Plugin settings from Roon UI
Roon’s API is still in a pretty early state, but 1.3 contains support for these features and is suitable for experimentation.
We have several exciting integrations planned over the next few months using the API as a jumping off point, and look forward to expanding and improving the Roon API with your feedback. Please try it out and let us know!