It doesn’t need to be that complicated.
I’m not sure I understand what you mean in this context of “frontend” vs “backend” - it sounds to me like they’re just different pages within the same “system”.
I’m a member of the “One app unless proven otherwise” camp. I don’t know how many pages you’re looking at, or whether you’re planning on using one of these apps in multiple applications, but I’d start building this as one app using the same structure as the tutorials you’ve worked through. One project, one app.
(There are a couple other threads here in the forum talking about one vs multiple apps. See Why do we need apps? and Project organization- when is something a separate app?)