Wellll… Probably not Kirby Star Allies, unless you intend to clear Guest Star Ally ???? Go! as every character, but maybe Smash. Tennis Aces didn't take me long, but %100ing Luigi's Mansion 3 might take a bit.
Super Mario Boards
Mags
Teedgee
most of the games you mentioned i already have (kirby star allies and smash), but i was thinking of giving lm3 a go. however i'm just waiting to see if there's any better game i could get
zel
legit the only game ive heard of that actually takes hundreds of hours to complete is the funny personer the fifth but thats not on switch. so prob the lenghiest switch game i have is mario odyssey with around ? 30 or so hours just to beat the game and a whole bunch more from the postgame. you prob already have that doe!
Alex95
Dragon Quest XI S
Blue
Paper Mario: The Origami King
Lakituthequick
The Legend of Zelda: Breath of the Wild