That's because Google is once removed from TSMC, unlike Nvidia and Apple
Google and Broadcom are in co-design partnership (and now also MediaTek). Google defines the architecture. Broadcom provides the essential infrastructure (IP blocks) that makes the chip work on silicon and works tight with TSMC to make it happen in new nodes. Spending billions to help Broadcom get into par with Nvidia is not what they want.
Apple, for example, designs nearly the entire SoC in-house (CPU, GPU, NPU) and work with TSMC hand in hand. They buy only specific chips and block designs like Wi-Fi, Bluetooth, and RF.