What's hard about VS? File -> New -> Arduino Project -> <name the project> and up comes a new document with setup() and loop() predefined. Click on the green ball icon to compile and upload the sketch.
Exactly the same process as the Arduino IDE.
There are probably some issues to work through but it shouldn't be all that difficult.
The Arduino IDE is less than optimal but it does get the job done.
You do realize the kid is 8, right? You know how to use this, I know how to use it, but someone who has never seen VS is going to be utterly lost in the maze of menus and irrelevant crap that is in it.
Also installing the damn thing takes a few hours if you are unlucky, plus several gigs of download.
I concur with @Timb - if the primitive (and honestly infuriating) editor is not an issue, then the Arduino IDE is the best choice. All the tutorials are written with it in mind too.
If one wants something better (which I assumed since use of external editor was mentioned) then I would go for that PlatformIO (no need to fiddle with the integration like for Notepad++).
I didn't give Visual Studio even to my university students when they were learning to program in C - it is just an enormous distraction and I wouldn't have been doing anything else than troubleshooting VS issues instead of actually teaching. Basic editor is just fine for that and they were free to "upgrade" to a full IDE later when they actually knew what they were doing in terms of compilation, linking, finding libraries, etc.
If I have done it in reverse (aka started with a full IDE), they would have learned that if the thing complains about a missing header they have to click here there and there to fix it - and would have been lost because XCode on their laptop or Eclipse later doesn't call the things the same nor are they in the same place. Many (not all) Eclipse "haters" are the product of this approach - all they have ever learned is how to use VS or XCode or whatever and when suddenly faced with another IDE with a different design philosophy they struggle to adapt. Which sucks for an engineer, IMO.