Is MonitorControl safe to use on a Mac?

Yes, MonitorControl is safe. It's free, open-source (MIT-licensed, 32k+ GitHub stars) and widely trusted. It talks to your screen over standard DDC/CI, the same protocol your monitor's own buttons use. The catch for you: it controls external monitors, not your built-in MacBook Pro panel's brighter reserved range. On an Apple display it just moves the normal F1/F2 brightness macOS already gives you. It can't push a Pro 14"/16" or Pro Display XDR past the macOS cap to about 1,600 nits. That reserved range is the one job MacBrightness opens, system-wide, on the same keys, for $5 one-time. Try it free first with Splitscreen Mode.