Valve is the only user of the AMD "Van Gogh" APU. Other handhelds are using regular laptop parts.

I think AMD originally pitched it for laptop makers since it was leaked in 2020: https://videocardz.com/newz/amd-mobile-apus-for-2021-2022-de...

But I suspect they rejected it because they don't care about IGP performance, just as they rejected Intel's "Iris" Broadwell CPUs and the hybrid amd/intel chip.