Earlier this year, we were expecting Microsoft to hold a Surface event in March, where it would announce the Surface Go 2 and the Surface Book 3. Obviously this didn't happen, thanks to the COVID-19 coronavirus pandemic. But the products are still on the way, likely in May.
As is typically the case when new products are about to arrive, the old ones are selling out and stock isn't being replenished. That's the case with the Surface Go, which is now completely out of stock in the Microsoft Store on the consumer model. For the Surface Go for Business, only the base model is available, with the other three configurations being sold out.
As for the Surface Book 2, that's not completely sold out, but most configurations are. You can get the 13.5-inch base model with a seventh-gen Core i5, the Core i7 model with 8GB RAM and 256GB storage, or the Core i7 model with 16GB RAM and 512GB storage. For the 15-inch variant, you can only get the base model with an eighth-generation Core i5 and no dedicated GPU.
The Surface Go 2 is expected to include an Intel Pentium Gold 4425Y processor from the Amber Lake family, and Surface Book 3 is expected to use Intel's Ice Lake processors and newer Nvidia GPUs. We should hear more about them in May.