Yeah, i think there are generally two ways to go about it: invent the wheel, or steal it.
Given that Recalbox already has solved this problem, I would tend to go towards the latter option. However, Recalbox has seen MANY more commits over the last year, so the overall delta in terms of dependencies might be rather big.
I am planning to do some more digging, and see what is used for sound handling in de current ES, because i think its different from what is used in Recalbox (which also supports *.ogg files).
Also, What are our requirements for this function?
A single background track for all systems?
That seems like a reasonable starting point.
Send from mobile, please excuse any brevity and typos.