The current Switch has its Joy-Con controllers attach by sliding through a railing on the side until a locking mechanism clicks them into place. Owners then press a very (very) small black button on ...
A separate video from Nintendo's Switch 2 first-look trailer highlights how the Joy-Con controllers will easily disconnect from the console.
The Switch's producer was "particularly excited" about the idea at the time, but it didn't work well enough back then ...