I'm wondering if it's possible to distribute an tvOS app IPA to - in my case - clients, such that they can install it on their Apple TV without Xcode and not via TestFlight. On iOS one can use an ITMS link to the correct manifest plist and IPA. Is there any similar method for tvOS?
Ad-hoc distribution of tvOS IPA
No. There's no web browser on the Apple TV with which to open a link. And there's no interface in iTunes to install apps even if the user did manage to find the correct cable to hook it up.