Afraid of switching to Catalina for fear of losing 32-bit app compatibility?
Fret not, for a simple invocation will allow your 32-bit apps to run natively on macOS Catalina, with no frills.
It appears that Apple has not removed 32-bit capability from the Darwin kernel itself but merely disabled it, in addition to stripping all the 32-bit libraries from the system.
To re-enable 32-bit processing from the kernel, simply add no32exec=0 to your boot arguments (by invokingsudo nvram boot-args="no32exec=0" if System Integrity Protection is disabled, if not by running the same command from Recovery mode).
To get the 32-bit libraries back, you will need to copy them over from Mojave (preferably 10.14.6) or add the following prefix when executing the app through the Terminal:
DYLD_ROOT_PATH="\Volumes\<MacOS_Mojave_Root>" ./<YourApp>Where <MacOS_Mojave_Root> is the path to your Mojave install’s root directory and <YourApp> is the path to your app.
Special props to Netkas and Max Coplan for the discovery.
