I don't know how practical this is on Apple hardware (I don't deal with hardware much overall, I'm a software guy), but in general, you can usually get by with

I don't know how practical this is on Apple hardware (I don't deal with hardware much overall, I'm a software guy), but in general, you can usually get by with just two SSDs/HDDs, each with a different OS instance on it, to separate work and home. Assuming, of course, your company would allow you to modify your work machine, if they gave it to you. A physical switch is pretty unnecessary, as you couldn't switch between systems without cutting power to one anyway (and basically nothing is stored outside the hard drives anyway); choosing a drive/OS on boot should be fine.