Emacs meta key in MacOS Terminal
In short, you can't remap the Command key in the built-in Terminal app.
So, instead: 1. Download iTerm2. 2. Preferences –> Profiles –> Keys –> Left Option key: Esc+ 3. Preferences –> Keys –> Remap Modifiers –> Remap Left Command to Left Option
This is a lot fucking easier than any other option out there and is great for running Emacs over SSH with Mosh. (Have you tried linode?)
I wish I had a better option for you, but this is what you have to do if you're running Emacs in the terminal.
I recently switched my entire life from GNU/Linux + Android to iPhone + MacOS and, honestly, it's helping me stop worrying about little bullshit and get on with my life's work.