Turns out the sky labyrinth was dead simple. My “reward” was getting to access ANOTHER labyrinth in the depths. It’s guarded by a tier 3 Zonai totem that can kill me in one hit and constantly teleport its weak spot out of reach. I bailed.
Went for one last romp around Hebra, finishing a quest and getting more shrines. Ended up wandering west and getting the towers for the woodland and Eldin areas. Went to the depths along the way (why did Dinraal go down there?) and found a Yiga camp. There was one soldier piloting a Zonai car; hope to see crazier setups. Think I’m missing something crucial about devices to have fun with them, since I don’t understand how some I stumble across work. Final major upgrade: the first Great Fairy Fountain. Finally have a use for wagons in getting the band up there. Feels like I’m just now starting to find the meaningful content additions.