AMD is testing arm in the backend, but they have no incentive to switching to an ARM design at the moment. I fully believe both AMD and Nvidia are waiting for Qualcomm/Microsoft to iron out Windows for Arm before they release their projects. Nvidia of course has experience via tegra for linux via jetson. AMD is just making use of their advantageous situation on desktop/server market to not need to immediately shift to ARM.
With Ryzen x3D for consumers(desktop), and Ryzen #c cores for low power server core count/low power consumption/yields. they control a huge mind share and the only one they dont control is low power boards (<35W) devices as it’s not their current priority (theyre devouring the server market)
if its strictly nas, yeah thats a flaw. the advantage of the x86 devices is that the low power chips have good transcoding. so its common for people to pick up intel n series boards for intel quicksync, and the raw expansion ports for storage