There have been rumblings about this for a year or so, and it's interesting because Nvidia doesn't have any large hardware inclusions in the gaming space, aside from Switch 2. Nvidia has NVM as an API abstraction for their hardware, so I assume this job is about working on improving performance or support on that end.
Now, the big question is...why? It's unlikely they would do this to squeeze about more performance out of their existing hardware for PC and Switch users alone. I think the general speculation would be that they are planning a product launch of some sort, and from the sound of the posting, I'm guessing they've got something to compete with AMD in the handheld market that isn't Tegra.
They've also been saying for years they intend to hop into the ARM space, but keep fumbling it with delays. Their N1X(?) is supposed to finally launch "soon", but with component prices the way they are right now, I'd expect them to delay again. Their Grace chips were kind of a joke, and they didn't come anywhere near the power efficiency of other SoC options in the market.
All this to say: I think they're hiring a small dedicated team to improving mobile or ARM gaming chips for...something, and that's what these jobs are for. They need to squeeze some more juice from these chips to make them attractive at market.