They announced this year they would use Nvidia IP for automotive infotainment:
At Computex 2023, MediaTek announced a partnership with NVIDIA to deliver a complete range of in-vehicle AI cabin solutions for the next generation of software-defined vehicles. MediaTek’s CEO Rick Tsai took the stage with NVIDIA’s founder and CEO Jensen Huang to announce the collaboration, which…
www.mediatek.com
Then there were claims that partnership could extend to smartphone and laptop chips:
MediaTek’s next processor might pack an Nvidia GPU, signaling that Team Green could be getting serious about mobile games.
finance.yahoo.com
All of these announcements/rumors happened this year but they probably did a lot of research before-hand last year.
It kinda lines up with the rumors of devkits being recalled and a Nintendo project being canceled.
Mediatek being at the forefront of mobile tech:
MediaTek has achieved a technological breakthrough by developing the first chip using TSMC's advanced 3nm process. Set for mass production in 2024, this marks a significant milestone in the long-standing strategic relationship between MediaTek and TSMC. This partnership combines the strengths of…
www.mediatek.com
MediaTek and SK hynix have collaborated to verify that SK hynix's new LPDDR5T (Low Power Double Data Rate 5 Turbo) is ready for MediaTek’s next-generation flagship mobile platform. LPDDR5T is the latest development in mobile DRAM technology and is currently capable of achieving record-breaking…
www.mediatek.com
And probably also 5G and Wifi, they would be a far better partners than Nvidia for Nintendo, if they integrate Nvidia's IP right.
Nvidia are focused on their datacenter/GPUs businesses, they may want to license their IP for mobile, that's also why they wanted to buy ARM.
Mediatek is investing in mobile AI and RT:
MediaTek and Unity China Collaborate on Raytracing and Generative AI Solutions to Create a New Standard for Next-Generation Mobile Gaming Experiences
corp.mediatek.com
A partnership with Nvidia makes a lot of sense.
Nvidia, Mediatek, Nintendo and others could be rallying behind a single software stack and framework, instead of each developing their own chips.