I did not have a launch.json file, and I did not have a Unity Debugger as an option to create one. After doing some searching, this is how I solved it:
“To switch to mono you need to go to VS Studio Code: File → Preferences → Settings. In Settings search for ‘mono’ at the top and then change Omnisharp: Use Global Mono from ‘auto’ to ‘always’. After doing this you can click the debug tool on the left bar and generate your launch.json file (note Unity only appears as an option for the drop down here if you are still in the Settings tab. Navigating back to your code files and trying to do so will not work, but everything shares the same .json file). Hope this helps future devs”
So keep that settings tab open, and choose Unity Debugger.