That's been the point of amiibos since 2014, to unlock extra/late content via NFC, otherwise they'd just be figurines (which is still the main point I guess). The specifics for these were also announced months ago, and they're also already released before the game, where have you all been?
It's also a reward for 100%ing the desert (cue complains about that I guess, because you want it earlier, not later, even though without the amiibo they'd likely never make it available early to begin with but nah, we'll twist this into the amiibo unlocks being the intended vanilla experience).
Hey guyz, I got a secret cheat for you to actually enjoy better features than the amiibos give, shhhh, don't tell Nintendo or they will send their ninjas to come for me too. Put some music on your phone or whatever folks, you can even put music that's not available even with the unlocks
I've only really wanted the woolly amiibo(s) without even having any compatible Nintendo things.
Introducing Green Yarn Yoshi amiibo (from Yoshi's Woolly World series)
www.nintendo.com
Introducing Pink Yarn Yoshi amiibo (from Yoshi's Woolly World series)
www.nintendo.com
Introducing Light Blue Yarn Yoshi amiibo (from Yoshi's Woolly World series)
www.nintendo.com
Introducing Poochy amiibo (from Yoshi's Woolly World series)
www.nintendo.com
I couldn't find any of them here though, sucks. They made a big one too but I don't find it as cute.
www.nintendo.com
Don't be jelly nkafaro, you're cute too, probably, to someone.