No. Precisely the Tegra SoC within the Nintendo Switch (X1) uses ARM Cores. Specifically A57 and A53. NVIDIA's project to develop their own v8.2 ARM-based chip is called Denver.
What do you define the difference between an in-house developed SoC with ARM-IP Cores and Denver's "ARM-based chip"? It is going to be a new architecture, but using a mix of ARM IP blocks and in-house IP following the ARM ISA?
Famously, the Tegra SoCs, as used in the Nintendo Switch.