If anyone happens to be interested, I have a PoC OTA deployment solution I built when I got tired of being asked for regular app builds. It's a Web service designed to run on a Mac and pull from a GitHub repository, run xcodebuild, package the IPA, and let you install it on your device.

I abandoded this because I longer have access to a Mac since I stopped iOS development a while ago, but ping me if you're interested and you want to try to get it to work. It doesn't come close to the features of something like TestFlight, but was designed for in-house use by a team who needs access to bleeding edge builds without developer intervention.