Build by day. Ship at night.
Connect to the same cloud Mac over SSH or its graphical interface. Use Xcode and the simulator for daytime development and testing. Before release, check your signing assets, then run fastlane beta in the evening to submit the build to TestFlight.
For a short release sprint, consider a daily or weekly term. Project files, build caches and release scripts stay on the node, so you can pick up where you left off next time without rebuilding your environment.