My project is 3d for the most part. But at least the game controls and menus are in 2D.
I chose in "Stretch": Mode:2d, Aspect: expand, Shring: 1
I would select the screen size of the iPhone 6Plus (which is describe as x2).
Godot should automatically scale up on devices with higher resolution (and scale down on lower res devices).
But:
I have doubts that you can be fast when your friend gives access to the mac book.
Especially the release & testing (maybe repeated) on the app store might take its time. Probably you will want to do a testing/beta release first where it takes some time until you get feedback from the testers.
It is basically possible to install MacOS in a VirtualBox but it is really a PITA because it is very,very,very slow. And i.e. the USB connection only worked via some network USB redirection tool. And just forget about running an emulator in VirtualBox it may theoretically work but it is slow. MacOSX Mojave (which will be required to run XCode 10.2 which is required when your phone runs iOS 12.2) runs extra slow .
If you have a PC with a very fast i7 and 8+GB RAM and much time you might give it a try though.
