But just look at them!
They’re mostly best treated as figurines that tend to have a very modest use in some games. My Yoshi one lets you dress a Mii up in a Yoshi suit in MK8, wonders off to get hints on where moons are in SM Odyssey or lets me save my stats in Smash Bros.
A few are treated a little more like DLC; I think there was a bit of controversy over a Zelda one and a couple of Metroid ones that basically locked additional content behind them, requiring the amiibo to access additional trials or mini games, that kind of thing. Those ones are NOT fun and generally suck big hairy monkey balls.