It looks as though the Nintendo Switch 2 Joy-Con controllers can magnetically snap into a little holder (similar to the first Switch) and then be used like a mouse.
We see this at the start of the trailer where we see the IR sensor on the new, larger Joy-Con and then it’s seen again at 1:10 in the reveal trailer where the Joy-Cons snap into a holder and then slide around in the trailer, showing that they can almost be certainly used in this way, similar to the Lenovo Legion Go which did the same.
If this is the case, this should definitely open up for some interesting gameplay opportunities for games such as Pikmin and Metroid Prime.