From what I can see, the reviewer wasn't happy about your screenshots. Specifically the top left corner of the screenshot has the word "TestFlight". Replace that screenshot with a one that doesn't mention TestFlight and re-submit the app. I recommend using the Xcode iOS Device Simulator to take screenshots. There's a button in the toolbar to save a screenshot, or the keyboard hsortcut is Cmd-S.. You should submit screenshots with at least the following screen sizes: 6.7" - iPhone 12 Pro Max 5.5" - iPhone 8 Plus 12.9" - iPad Pro (assuming your app makes sense on iPad) other screen sizes if you're willing to take the time

This wasn't the Facebook SDK for me - I had to spend an hour setting breakpoints and going through the code one line at a time to find it (ended up being some old logging code that was #ifdef'd out for the app store build). If anyone knows an easier way to find the cause of this alert, please do share. :)

And converting it to an MacOS project is not an option. Are you sure? With my app the process was pretty much just adding "My Mac" as a target, then hitting the run button. Just a guess here, but I suspect macOS will doing exactly the same thing, minus the recompile step, if you decide to deploy your app in the Mac App Store. I'm sure there are a bunch of APIs that work better on macOS 11 than they do on 10.15, but my app doesn't seem to be using any of them. Maybe yours won't either. As far as I know beta 2 isn't available yet for the DTK, so nobody [outside of Apple] knows if it will be possible to run ARM iOS apps on it. Also, there's no rush. There might be zero work involved in "porting" your app, other than testing it thoroughly, and the deadline to get it done is several months away.

Have you tried just using Xcode 11 on Mac OS 10.15 and use "My Mac" as the deployment target? You don't need to mess around with beta software to build an iOS app for Mac OS.

while signed into an account that has access to a DTK OK... so clearly my account doesn't "have access" to the DTK. How do I fix that?