The difference between other editors and pgAdmin is that pgAdmin can run on the web. Which means, a pgAdmin server hosted on linux can be opened on a Mac machine browser.
I'm working on removing the usage of Access Keys(which varies based on OS and Browser combination) for keyboard shortcuts and instead use shortcuts similar to all other IDEs.
The challenge here is OS. MacOS has an extra key - Meta, which pgAdmin doesn't take as part of keyboard shortcut currently. In fact, Mac can take Ctrl separately.
pgAdmin can run as a web app so it's even more difficult. It is not possible to have multiple shortcuts based on the OS of the browser.
I suggest we consider Ctrl as Meta when running on a Mac.