I’d look into App Roadmap created by Chris, for what technologies you can use to build your own app ideas.
Honestly it all depends on you for the order you want to do things. You can do the UI first and then the back end logic (database things) or vise vera.
Chris typically does UI first because it’s easier for beginners to understand.
You can check out how I built a simple quiz app by going through my story highlights on my Instagram