Unified memory is a lot more flexible and efficient though. You don't have to have assets loaded in RAM and also VRAM for the CPU/GPU to use them. Don't forget about how much more RAM a general purpose OS like Steam OS can consume versus a gaming specific OS too. The PS5 Pro also has an extra 2GB of DDR5 system RAM too.
My old Ryzen 3700X gaming PC has 16GB of RAM and 8GB of VRAM (RTX 2070 Super) and there isn't any game that runs better on it than my Xbox Series X. And the GPU in the Steam Machine is slightly worse than an RTX 2070 Super.
My old Ryzen 3700X gaming PC has 16GB of RAM and 8GB of VRAM (RTX 2070 Super) and there isn't any game that runs better on it than my Xbox Series X. And the GPU in the Steam Machine is slightly worse than an RTX 2070 Super.