I toggle between 3 different apps on Android and it seems that it took awhile until I received your comment. I guess everything is fresh here -- and it's all part of the fun!
Yes, Aztekium cacti grow very slowly (around 1mm in diameter per year), so people graft them to accelerate the growth. This one is 17mm big and I got it grafted already, never tried it myself.
First it looked a bit etiolated but now it's full of leaves 👏