One of the genuinely new features confirmed in the Switch 2 reveal was the Joy-Cons' ability to be used like a mouse, and in a newly public patent, Nintendo calls it exactly that.
In the Drawings tab of the patent's webpage, you can see a bunch of sketches of the Switch 2 and its new magnetically docking Joy-Cons. A handful of those show the Joy-Cons being used like you would a normal PC mouse, and in some cases, with one Joy-Con in each hand.
The patent abstract says the Joy-Cons have "a front surface, an upper surface, a first side surface, a second side surface, a direction input unit, a first upper surface button, and a sensor for mouse operation."
In the same description, Nintendo says "the sensor for mouse operation detects reflected light from a detected surface," which, yes, is exactly how a PC mouse works. I still fully expect for Nintendo to come up with some cute, quirky, Nintendo-y name for the Joy-Con's mouse function, but it's good to have full confirmation of Nintendo's intent behind the thing.
Of course, the larger question still looming is how exactly Nintendo wants us to use the Joy-Con mouses. You can safely expect it'll be used in a gimmicky way in conjunction with motion controls in various games, but I'm curious if it'll have more practical applications. If anything, I could see it making the process of typing stuff out a little quicker.
Hopefully we'll learn more during the Switch 2 Nintendo Direct in April.
