My experience with Hyperion on S905x / S912 boxes under CoreElec is that the LEDs are lit but really fluid I've never gotten this to work. You can use this tutorial quite well for setup I've installed Hyperion under LE on my Raspi4 with it and the performance is pretty good. Since I experiment with 4K HDR material, it is finally completed with a S905x2 box under CE as the optimal solution for me.
You can find DIY Ambilight a lot of tips and tricks on the net that's fun and you learn a lot in this way so nothing we ran;)
can you share your coreelec-arduino setup because i have a s905x2 h96 max x2 and searching through the internet it did not help me! sorry for the english!