In 2013, NVIDIA introduced the Shield Portable, its first-ever gaming handheld console to be powered by a Tegra 4 SoC. It wasn't widely available to the world, saw limited distribution, and despite being constantly out of stock, its parent company quietly halted production of the portable device years later, along with the Shield Tablet, a successor that was released in 2014.
At this point, you're probably asking 'But John, what about the Nintendo Switch? Didn't that launch before the Deck?' The answer is yes. Yes, it did. But the one thing you absolutely need to remember is that the Switch, while technically a handheld, came into the market as a competitor to the 'traditional' consoles, the PlayStation and Xbox.
At this stage, NVIDIA has two choices: Jump back on to the bandwagon with the creation of an all-new, console-centric and specific chipset, or tap into its already vast pool of currently existing chipsets that it made primarily for its self-driving and driving-assist programs for the automotive industry. After all, it wouldn't be the first time it would so.