To answer your question, as far as I know all the amiibo functionality apart from the announced wolf can be found in game, you just get it earlier with the amiibo. That's what I heard.
Guardian - rare weapons and other items
Bokoblin - rare clubs
Archer Link - new bow
Horse Link - new sword and sadle
Zelda - new shield
https://gamerant.com/legend-zelda-breath-wild-amiibo-221/
We have no idea if these itemes from the amiibo can break or not and if you can re summon them if...