@shawly
Great, thanks a lot! 
I created a feature request to extend the braviatv integration.
However, I will follow your example and build a rest bridge which I can utilize in the meantime (I am quite new to HA, but I think I see what you did there 
).
I kickstartered for a YIO-remote (Touchscreen remote for HA) and in the end I want to be able to get rid of the ugly original sony remote and control everything with YIO.