They do not. The CPUs are only there to support and push data to the GPUs. Much like Nvidia GH200 systems. Nobody buys these APU chips for their CPU parts.
For comparison there are 9,988,224 GPU compute units in El Capitan and only 1,051,392 CPU cores. Roughly one CPU core to push data to 10 GPU CUs.
Frontier is right behind it with the same arrangement.
Having honest to god dedicated GPUs on their own data bus with their own memory isn't necessarily the fastest way to roll.