The short answer: the one case in the verified set cut for the Legion Go 2 alone is the ivoler hard shell, and whatever you buy, it has to close over 50.85 mm of joystick height rather than the 42.25 mm body figure most listings quote. Everything below is how to tell a case cut for this machine from one cut for the 2023 one.
The question underneath every Legion Go 2 case listing is which machine it was actually cut for, and the answer is almost never in the title. Lenovo has now shipped three handhelds in this family, two of them 8.8 inch, and the aisle sells cases for all of them side by side.
Here is what Lenovo publishes, which turns out to be enough to settle it. The 2023 Legion Go measures 298.83 x 131 x 40.7 mm with its controllers on. The Legion Go 2 measures 295.6 x 136.7 x 42.25 mm. So the newer machine is slightly narrower, and it is meaningfully deeper and thicker. A case cut snugly around the older one has slack in the dimension that does not matter and a shortfall in the two that do.
Then there is the number almost nobody quotes. The 42.25 mm figure is the body. Lenovo adds, in a footnote to its own spec sheet, that the height is 50.85 mm with the joysticks. The sticks are the tallest part of this machine and they do not retract, so 50.85 mm is what a hard case has to close over. A listing quoting an internal depth in the low forties is quoting the wrong dimension.
This is an argument from published dimensions. We compile manufacturer specifications and owner reports; we have not put a 2023 case on a Legion Go 2 and this page does not pretend otherwise.