I have a client that wants to release a new version of their app (new IPA) for a specific country, but keep the old IPA available for other countries for an undetermined amount of time. The app needs to have the same name, only users in this specific country will get the new version. Other countries will get the new one eventually.
Both IPA's currently have the same bundle ID, so the store listing/location will be the same.
Will Apple even allow this? I am trying to find documentation from Apple that states that multiple IPA's/binaries are not allowed for the same app. I don't even think you can select more than one binary when you upload to iTunes connect, if I remember correctly.
Note that making another target is not an option as the A) the codebases are separate and B) the client doesn't want to create another store listing.
You can not publish multiple versions at the same time, this includes regional segmentation. You can, however, limit availability of the app and leave only those regions that you want to keep supporting. This can be done at the Availability section at iTunes Connect: https://developer.apple.com/library/content/documentation/LanguagesUtilities/Conceptual/iTunesConnect_Guide/Chapters/ChangingAppStatus.html
Note that users from the removed regions will not be able to open the app's page in the App Store until you extend availability back. Not sure what happens on the devices with the app already installed, it will probably remain functional, but will not receive updates.