Cactus seedling ID?

Hello fellow collectors. Would anyone be able to ID this little critter? My first thought for some reason was Denmoza sp., then Oroya sp., but now I'm not sure what it is. Its ID will determine whether I risk planting it outdoors (Sydney northern suburbs):

Hi, you can find in the genus Matucana.

Un saludo

Thanks heaps! I had another check-through and I think now it's Matucana comacephala.