patbl

Those instructions used to work for me. But when I followed them with Emacs 27.1, Emacs refused to start. Chris Farber, the author the blog post referred to earlier, posted a workaround in a comment.

That's in the Dock.

I've noticed that tell applications "Emacs" to activate is a bit laggy compared to the normal "Launch Apps / Files" action. Sometimes it takes a couple of seconds to change focus.

In fact, that works as expected. Clicking it the first time launches Emacs, and clicking it subsequent times switches focus to Emacs. Thanks, that works! That's good enough for me.

I have the same problem. I have a workflow that used to launch Emacs if it wasn't open, and switch focus to it if it was open: This worked on Mojave. On Catalina, the shortcut launches the app if Emacs isn't yet running. But if Emacs is running, the shortcut doesn't do anything.