I can confirm that exported IPA files are NOT accepted by "Transporter". These are the new error messages produced during validation (with ID's removed just in case):
Asset validation failed (90045)
Invalid Code Signing Entitlements. Your application bundle's signature contains code signing entitlements that are not supported on iOS. Specifically, key 'UIRequiredDeviceCapabilities' in 'Payload/Dungeons and Dice.app/Dungeons and Dice' is not supported. (ID: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx)
Asset validation failed (90502)
Invalid Bundle. Your binary, 'com.worldbydesign.dungeonsdice', has a 64-bit architecture slice, so you must include the "arm64" value for the UIRequiredDeviceCapabilities key in your Xcode project. Learn more (https://developer.apple.com/library/content/documentation/General/Reference/InfoPlistKeyReference/Articles/iPhoneOSKeys.html#//apple_ref/doc/uid/TP40009252-SW3). (ID: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx)
Asset validation failed (90208)
Invalid Bundle. The bundle Dungeons and Dice.app does not support the minimum OS Version specified in the Info.plist. (ID: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx)
This was using the newest AppGameKit Studio v2023.07.17 on quite an old Mac Mini (the only one I have available) macOS 10.13.6 - 2.5 GHz Intel Core i5 (4GB RAM).
Just for reference, the previous version of AppGameKit Studio (v2023.01.25) produced the following error when validating with "Transporter":
Asset validation failed (90725)
SDK version issue. This was built with the iOS 15.5 SDK. All iOS and iPadOS apps submitted to the App Store must be built with the iOS 16.1 SDK or later, included in Xcode 14.1 or later. (ID:xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx)