Any way to use @disableif if a drive is connected or not

as title, would like the button to be disabled if a certain drive is not connected/on.

I don't think there's an easy way. You can have buttons react to whether a path exits or not, when they run, but not enable/disable based on it (mainly because it'd cause a lot of extra filesystem access and possibly delays every time the toolbars refreshed, which is frequently).

You could have a script which checks the drive and sets a variable that the button tests in @disableif, but that's more complex.