It won't be user-facing, so there won't be an SDK. It's a way of building chips better,like AMD's Infinity Fabric. You could integrate GPUs, multiple CPU dies (like Epyc), and DRAM on a single package and tie them all together with interposers, which would look to the user like a CPU with an integrated GPU and a big L4 cache.

Using multiple small dies and tying them together has several advantages. Small dies yield better, so sometimes several small dies are cheaper than one large one. There's also versatility because you can mix and match components.