Free open-source iOS 12 iPad/iPhone second monitor for Mac. OpenDisplay-compatible client over USB/Lightning & Wi-Fi. Sidecar/Duet alternative for old devices.
Low-latency screen streaming from Apple Silicon to a 2010 iMac on OS X 10.9. Hardware H.264 over RTP/UDP, virtual display, zero-copy OpenGL rendering.
Use an old jailbroken iPad (iOS 6+, tested on iPad 2) as a real extended display for your Mac, over USB or Wi-Fi. Native iOS 6 app with libjpeg-turbo NEON, ~35 fps.