It's better off if I let Digital Foundry take it from here: https://youtu.be/BDvf1gsMgmY

TL:DW - it's not quite the full-fat CNN model but it's also not a uselessly pared-back upscaler. Seems to handle antialiasing and simple upscale well at super low TDPs (<10w).

Ok, but that's still nVidia DLSS tech from desktop, what's Nintendo in-house about it?

It's literally not. From the description of TFA:

  In this video, Alex goes in-depth on Switch 2 DLSS, confirming that there are actually two different forms of the technology available - the DLSS we know from PC gaming and a faster, far more simplified version.