[notreallyserio]

What is easy here? In Chrome, on macOS, it's command-` to switch windows and command-shift-m to open a new window in with a specific profile.

Also, links always open in the profile that is currently in the foreground. Is that possible in Firefox? Last I heard it isn't, but I haven't checked in a while.

[Isthatablackgsd]

Yes, there is but I don't know if it works for macOS since it works for me in Windows.

Set the profile you prefer to open for links as a default profile and make sure to tick the option to automatically use the default profile without opening the profile manager. Then for the second profile, you need to use the shortcuts for that with the argument like this

firefox.exe -P "<profile_name>"

And make sure you leave it as capitalized P, I believe that is the argument. Then apply the setting and click the shortcut. It should be opening links to the default profile that you set in the profile manager.