My understanding is that later pre-Zen APUs and Zen chips all essentially have the HSA hardware side... it's just that AMD never managed to prepare a long-term

My understanding is that later pre-Zen APUs and Zen chips all essentially have the HSA hardware side... it's just that AMD never managed to prepare a long-term coherent software offering like nvidia did with CUDA. So outside of one-offs or very closed platforms like consoles, the HSA capabilities were just... lying there, used as super fast PCI-e alternative to access the GPU. Now consider that with Phoenix Point APUs you have Zen 4 CPU, memory controllers, IO controller, RDNA3 GPU, and the XDNA "transputer-like" coprocessor, all hanging off common cache coherent transport (Infinity Fabric). All the hardware parts are there.