How is Hugo photo publishing effortless?

Also what is the Hugo iOS experience?

All I do is put photos inside my Hugo blog folder and then reference it in my markdown files. I’m not sure how it could be simpler than that.

I also don’t understand why someone would want an iOS app for a blog. What’s the use case?

Well if you have the build automated, you can simply use a markdown editor and commit the file into git. It's not like an experience like Wordpress but i would say it's not that bad.