I also want to know this. The market for good aptX or aptX HD compatible headphones and speakers is growing steadily, so this is becoming more and more important.
Currently, I am involved in a product test of the Beyerdynamic Aventho Wireless headphones, which support aptX and aptX HD. And the FP2 supports neither. This could become a dealbreaker in the future…
Addendum: I am using LineageOS and with a simple addon I enabled aptX for my FP2. So right now I am happy, and I am also wondering why this was not possible with the stock firmware - the hardware capability seems there…
I’d guess licensing restrictions. Either licensing fees are due for the drivers. or for the use of the hardware capability (as some variant of crippleware - where it’s cheaper for the SoC manufacturer to bake capability into all SoCs, but only enable use of the feature for those customers who paid the relevant royalties and licensing fees). The XDA page suggests licensing differences as well.