Gothenburg recommendations

I’m travelling to Gothenburg (for the first time) next weekend with my 4.5 year old son for 2 nights - a little mum & son trip before he starts school. We’re staying in Haga, I was wondering if anyone had any recommendations of places to eat (cafes etc) - or any other things to do!

All he has specified so far is that we must visit the Moomin shop 🥲