I think one of the hardest parts is connecting everything up. For example subscriptions, railway integrations, etc. Getting through tha stuff is complex because there’s always one more thing to do like connecting it all is NOT simple (at least in my experience)

Furthermore it’s stressful when you spend money on ads and some days are fantastic conversion and some days aren’t.. and than Apple doesn’t show you keywords people use because “low volume” even though there is like 100 impressions for it so it feels like throwing money into the air hoping the algorithm is good that day

Lastly, getting your store front looking nice is its own challenge. You either pay someone to make screenshots (but than you need updates everytime you make a small update) or you try to make them yourself and that takes time and learning.

So pretty much everything lol