This page describes how to get the Handy Atari Lynx emulator running on macOS. There is a download package for macOS available here. You will also need to download the Atari Lynx BIOS.
1. Unzip both the handy-098.zip and LynxBoot.zip files. If you try to run Handy.app now, you will get the following error message (which has an incorrect path so do not follow instructions from that error message)...
The Lynx Boot ROM image couldn't be located!
The lynx emulator will not run without the Boot ROM image. "lynxboot.img" must be placed in ~/Library/Application Support/Handy/BIOS ROMs/. This is not supplied with the emulator, do not ask me to send you this file.
2. Open the Terminal.app and run the following commands (assuming you unzipped the files in the Downloads directory)...
mkdir -p ~/Library/Application\ Support/Bannister/Handy/BIOS\ ROMs
cp ~/Downloads/lynxboot.img ~/Library/Application\ Support/Bannister/Handy/BIOS\ ROMs
3. Run Handy.app, it will ask you to select a ROM file to load...
The ROM should run now, here is Turkey Puncher 3 running in the emulator...