Simple (experimental) app that maps left/right tap to left/right click. Accessibility permissions need to be enabled to access the touch events. The app works fine for me on Catalina, but use at your own risk.
If you want more features check out Multitouch.app or BetterTouchTool.
Download the code and build it in Xcode. There is no released app because I don't vouch for its stability.
This is a fork of MiddleClick, even though the functionality is completely different. The code has been substantially changed as well - I've mainly reused part of their event-callback setup, and the app icon.
Thanks to @calftrail for reverse engineering the Multitouch framework.